The title affirms this to be a psalm of David, and there is no reason to doubt the correctness of the superscription; but there are no indications by which we can determine on what occasion it was written.
It is not difficult, however, to ascertain from its contents the state of mind in which it was composed; and as that state of mind is not uncommon among those who are the professed people of God, the psalm will be useful in all ages of the world. The state of mind is that in which there is deep solicitude in regard to personal piety, or on the question whether the evidences of our piety, are genuine, and are such as we may rely on as warranting our hope of salvation. In this state of mind, and under this deep solicitude, the psalmist appeals to God to search him, or to judge in his case; he then recounts the evidences on which he relied as a ground for concluding that he was truly a friend of God; and then expresses the earliest desire of his heart to be found among the friends of God, and not to be united in character or in destiny with the wicked.
The psalm, therefore, properly consists of three parts:
I. A solemn appeal to God, or an earnest prayer that He would examine and judge of the evidences of piety on which the psalmist was accustomed to rely, Psalm 26:1-2. He was conscious of integrity or uprightness of intention, but he still felt that there was a possibility that he might deceive himself, and he, therefore, prays that God would search his heart and try his reins - that He would examine the evidences of his personal piety, and save him from delusion.
II. A statement of the evidences on which he relied, Psalm 26:3-8.
These evidences were the following:
(1) That God's loving-kindness was before his eyes, and that he had walked in his truth, Psalm 26:3.
(2) That he had not been the companion of the wicked, nor had he delighted to associate with them, Psalm 26:4-5).
(3) The desire of his heart to approach the altar of God with purity, and to celebrate the praises of God; or his delight in public worship, Psalm 26:6-7.
(4) That he had loved the place where God dwelt, or the habitation of his house, Psalm 26:8.
III. His earnest wish to be found among the friends of God, or to have his portion with them, Psalm 26:9-12.
(1) His "prayer" that this might be his lot, Psalm 26:9-10.
(2) His "purpose" to walk with the just and the holy, or to be found among the friends of God, Psalm 26:11-12.
In reference to all this, he asks the guidance and direction of God; he prays for the searching of His eye; he pleads that God would enable him sincerely to carry out these desires and purposes of his soul. The psalm is a beautiful illustration of the nature of true religion, and of the desire of a truly pious man that all the evidences of his piety - all which is his ground of reliance - may be submitted to the searching eye of God.

The psalmist appeals to God for his integrity, and desires to be brought to the Divine test in order to have his innocence proved, Psalm 26:1-3; shows that he had avoided all fellowship with the wicked, and associated unth the upright, Psalm 26:4-8; prays that he may not have his final lot with the workers of iniquity, Psalm 26:9, Psalm 26:10; purposes to walk uprightly before God, Psalm 26:11, Psalm 26:12.
This Psalm, and the two following, are supposed by Calmet to be all parts of one ode, and to relate to the time of the captivity, containing the prayers, supplications, complaints, and resolutions of the Israelites in Babylon. This is probable; but we have not evidence enough to authorize us to be nice on such points. See on Psalm 26:1 (note).

INTRODUCTION TO PSALM 26
Psalm of David. The occasion of this psalm seems to be the quarrel between Saul and David, the former listening to calumnies and reproaches cast upon the latter, and persecuting him in a violent manner. The argument of it is the same, in a great measure, with the seventh psalm, and is an appeal made to God, the Judge of the whole earth, by the psalmist, for his innocence and integrity; Theodoret thinks it was written by David when he fled from Saul.

David, in this psalm, appeals to God touching his integrity.

The Longing of the One Who Is Persecuted innocently, to Give Thanks to God in His House
Ps. 25 and Psalm 26:1-12 are bound together by similarity of thought and expression. In the former as in this Psalm, we find the writer's testimony to his trust in God (בּטחתּי, Psalm 25:2; Psalm 26:1); there as here, the cry coming forth from a distressed condition for deliverance (פּדה, Psalm 25:22; Psalm 26:11), and for some manifestation of mercy (חנּני Psalm 26:11; Psalm 25:16); and in the midst of theses, other prominent points of contact (Psalm 26:11; Psalm 25:21; Psalm 26:3; Psalm 25:5). These are grounds sufficient for placing these two Psalm close together. But in Psalm 26:1-12 there is wanting the self-accusation that goes hand in hand with the self-attestation of piety, that confession of sin which so closely corresponds to the New Testament consciousness (vid., supra p. 43), which is thrice repeated in Ps 25. The harshness of the contrast in which the psalmist stands to his enemies, whose character is here more minutely described, does not admit of the introduction of such a lament concerning himself. The description applies well to the Absolomites. They are hypocrites, who, now that they have agreed together in their faithless and bloody counsel, have thrown off their disguise and are won over by bribery to their new master; for Absolom had stolen the hearts of the men of Israel, 2-Samuel 15:6. David at that time would not take the Ark with him in his flight, but said: If I shall find favour in the eyes of Jahve, He will bring me back, and grant me to see both it and His habitation, 2-Samuel 15:25. The love for the house of God, which is expressed herein, is also the very heart of this Psalm.