Oded is by some identified with Iddo, the prophet and historian of the two preceding reigns. In the Hebrew the two names differ very slightly.

Azariah the son of Oded - We know nothing of this prophet but what is related of him here.

And the Spirit of God came upon (a) Azariah the son of Oded:
(a) Who was called Obed as his father was, (2-Chronicles 15:8).

And the Spirit of God came upon Azariah the son of Oded,.... The same with Iddo, as Hillerus (h) thinks; and some suppose this to be the name of the son as well as the father, but called Azariah, to distinguish him from him, see 2-Chronicles 15:8 on whom came, as the Targum, the spirit of prophecy, instructing him what to say to Asa; and the Jews say (i) he is the same with Iddo, and he the same that was sent to Jeroboam, to reprove him for the altar he built.
(h) Onomastic, Sacr. p. 458. (i) In Hieron. Trad. Hebrews. in Paralipom. fol. 84. L. & 85. A.

The work of complete reformation appeared so difficult, that Asa had not courage to attempt it, till assured of Divine assistance and acceptance. He and his people offered sacrifices to God; thanksgiving for the favours they had received, and supplication for further favours. Prayers and praises are now our spiritual sacrifices. The people, of their own will, covenanted to seek the Lord, each for himself, with earnestness. What is religion but seeking God, inquiring after him, applying to him upon all occasions? We make nothing of our religion, if we do not make heart-work of it; God will have all the heart, or none. Our devotedness to God our Saviour, should be avowed and shown in the most solemn and public manner. What is done in hypocrisy is a mere drudgery.

JUDAH MAKES A SOLEMN COVENANT WITH GOD. (2-Chronicles 15:1-15)
Azariah the son of Oded--This prophet, who is mentioned nowhere else, appears at this stage of the sacred story in the discharge of an interesting mission. He went to meet Asa, as he was returning from his victorious pursuit of the Ethiopians, and the congratulatory address here recorded was publicly made to the king in presence of his army.

The prophet Azariah's exhortation to faithful cleaving to the Lord, and the solemn renewal of the covenant. - 2-Chronicles 15:1-7. The prophet's speech. The prophet Azariah, the son of Oded, is mentioned only here. The conjecture of some of the older theologians, that עודד was the same person as עדּו (2-Chronicles 12:15; 2-Chronicles 9:29), has no tenable foundation. Azariah went to meet the king and people returning from the war (לפני יצא, he went forth in the presence of Asa, i.e., coming before him; cf. 2-Chronicles 28:9; 1-Chronicles 12:17; 1-Chronicles 14:8). "Jahve was with you (has given you the victory), because ye were with Him (held to Him)." Hence the general lesson is drawn: If ye seek Him, He will be found of you (cf. Jeremiah 29:13); and if ye forsake Him, He will forsake you (cf. 2-Chronicles 24:20; 2-Chronicles 12:5). To impress the people deeply with this truth, Azariah draws a powerful picture of the times when a people is forsaken by God, when peace and security in social intercourse disappear, and the terrors of civil war prevail. Opinions as to the reference intended in this portrayal of the dreadful results of defection from God have been from antiquity very much divided. Tremell. and Grot., following the Targ., take the words to refer to the condition of the kingdom of the ten tribes at that time; others think they refer to the past, either to the immediately preceding period of the kingdom of Judah, to the times of the defection under Rehoboam and Abijah, before Asa had suppressed idolatry (Syr., Arab., Raschi), or to the more distant past, the anarchic period of the judges, from Joshua's death, and that of the high priest Phinehas, until Eli and Samuel's reformation (so especially Vitringa, de synag. vet. p. 335ff.). Finally, still others (Luther, Clericus, Budd., etc.) interpret the words as prophetic, as descriptive of the future, and make them refer either to the unquiet times under the later idolatrous kings, to the times of the Assyrian or Chaldean exile (Kimchi), or to the condition of the Jews since the destruction of Jerusalem by the Romans up till the present day. Of these three views, the first, that which takes the reference to be to the present, i.e., the state of the kingdom of the ten tribes at that time, is decidedly erroneous; for during the first thirty years of the existence of that kingdom no such anarchic state of things existed as is portrayed in vv. 5 and 6, and still less could a return of the ten tribes to the Lord at that time be spoken of (2-Chronicles 15:4). It is more difficult to decide between the two other main views. The grounds which Vitr., Ramb., Berth. adduce in support of the reference to the times of the judges are not convincing; for the contents and form (2-Chronicles 15:4) do not prove that here something is asserted which has been confirmed by history, and still less is it manifest (2-Chronicles 15:5) that past times are pointed to. Whether the statement about the return to Jahve in the times of trouble (2-Chronicles 15:4) refers to the past or to the future, depends upon whether the past or future is spoken of in 2-Chronicles 15:3. But the unquiet condition of things portrayed in 2-Chronicles 15:5 corresponds partly to various times in the period of the judges; and if, with Vitr., we compare the general characteristics of the religious condition of the times of the judges (Judges 2:10.), we might certainly say that Israel in those times was without אמת אלהי, as it again and again forsook Jahve and served the Baals. And moreover, several examples of the oppression of Israel portrayed in 2-Chronicles 15:5 and 2-Chronicles 15:6 may be adduced from the time of the judges. Yet the words in 2-Chronicles 15:6, even when their rhetorical character is taken into account, are too strong for the anarchic state of things during the period of the judges, and the internal struggles of that time (Judges 12:1-6 and 2 Chron 20). And consequently, although Vitr. and Ramb. think that a reference to experiences already past, and oppressions already lived through, would have made a much deeper impression than pointing forward to future periods of oppression, yet Ramb. himself remarks, nihilominus tamen in saeculis Asae imperium antegressis vix ullum tempus post ingressum in terram Canaan et constitutam rempubl. Israel. posse ostendi, cui omnia criteria hujus orationis propheticae omni ex parte et secundum omnia pondera verbis insita conveniant. But, without doubt, the omission of any definite statement of the time in 2-Chronicles 15:3 is decisive against the exclusive reference of this speech to the past, and to the period of the judges. The verse contains no verb, so that the words may just as well refer to the past as to the future. The prophet has not stated the time definitely, because he was giving utterance to truths which have force at all times,
(Note: As Ramb. therefore rightly remarks, "Vatem videri consulto abstinuisse a determinatione temporis, ut vela sensui quam amplissime panderentur, verbaque omnibus temporum periodis adplicari possent, in quibus criteria hic recensita adpareant.")
and which Israel had had experience of already in the time of the judges, but would have much deeper experience of in the future.
We must take the words in this general sense, and supply neither a preterite nor a future in 2-Chronicles 15:3, neither fuerant nor erunt, but must express the first clause by the present in English: "Many days are for Israel (i.e., Israel lives many days) without the true God, and without teaching priests, and without law." רבּים ימים is not accus. of time (Berth.), but the subject of the sentence; and אלה ללא is not subject - "during many days there was to the people Israel no true God" (Berth.), - but predicate, while ל expresses the condition into which anything comes, and לא forms part of the following noun: Days for Israel for having not a true God. ללא differs from בּלא, "without," just as ל differs from בּ; the latter expressing the being in a condition, the former the coming into it. On אמת אלהי, cf. Jeremiah 10:10. אמת כּהן is not to be limited to the high priest, for it refers to the priests in general, whose office it was to teach the people law and justice (Leviticus 10:10; Deuteronomy 33:10). The accent is upon the predicates אמת and אמת. Israel had indeed Elohim, but not the true God, and also priests, but not priests who attended to their office, who watched over the fulfilment of the law; and so they had no תּורה, notwithstanding the book of the law composed by Moses.

Spirit of God - Both to instruct him what to say, and to enable him to say it plainly and boldly.