The occasion and the author of this psalm are alike unknown. DeWette regards it as a temple-psalm, and agrees with Rosenmuller in the supposition that it was sung either at the beginning or the end of the service in the temple. Knapp supposes that it was used as an intermediate service, sung during the progress of the general service to vary the devotion, and to awaken a new interest in the service, either sung by a choir or by the whole people.
In many manuscripts of Kennicott and De Rossi, and in several editions of the Scriptures, this psalm is united with the following. The psalm has no independent character or meaning of its own, and seems to have been designed, like the "Doxologies" in our Books of Psalm and Hymns, to be attached to other psalms as occasion might require. There is no psalm designed for public worship to which it might not thus properly be attached.

The psalmist calls upon the nations of the world to praise the Lord for his mercy and kindness, and for the fulfillment of his promises, Psalm 117:1, Psalm 117:2.
This is the shortest Psalm in the whole collection; it is written as a part of the preceding in thirty-two of Kennicott's and De Rossi's MSS., and is found thus printed in some ancient editions. The whole Psalm is omitted in one of Kennicott's and in two of De Rossi's MSS. It celebrates the redemption from the Babylonish captivity, the grand type of the redemption of the world by our Lord Jesus.
The Syriac says: "It was spoken concerning Ananias and his followers when they came out of the furnace; but it also foretells the vocation of the Gentiles by the preaching of the Gospel." In this way St. Paul applies it, Romans 15:11.

INTRODUCTION TO PSALM 117
The inscription of this psalm in the Syriac version is,
"it is said concerning those of the house (or the companions) of Ananias, when they came out of the furnace; likewise it foretells the calling of the Gentiles by the declaration of the Gospel.''
Which last is right; for the apostle has quoted it, to prove the Gentiles should glorify God for his mercy, Romans 15:9. Aben Ezra thinks it concerns only the nations subdued by David; but he quotes R. Moseh, as of opinion that all nations are comprehended: and Kimchi affirms that the psalm belongs to the times of the Messiah; and supposes there is a mystery in its consisting of two verses only; and that it intimates that in those times there will be two people that will serve the Lord; Israel, with the law; and the Gentiles, with the seven precepts of Noah. It certainly refers to Gospel times, and to the conversion of the Gentiles; and when Jews and Gentiles should make one people, and be partakers of the same privileges and blessings; receive the same doctrines, submit to the same ordinances, and be under the same law, to Christ their King.

All people called upon to praise God.