English Basic Explanation - Chapter 117
This chapter, the shortest of all the Psalms (spanning only two verses), is the fifth chapter in the series of Tehillim that comprise the Hallel service. The Psalmist here calls upon "all the nations" to join in giving praise to the Almighty, because of the immense kindness that He has bestowed upon Am Yisrael. The Radak explains this chapter as referring to the time of Mashiah, when Israel will be redeemed and all nations on earth will come to recognize God. Ibn Ezra, by contrast, maintains that David speaks here of the nations that came under his control during his reign.
Either way, this chapter expresses the notion that the redemption of Israel – either during the time of King David, or during the time of his descendant, the Mashiah – will be followed by the nations' praise of God. When Am Yisrael experiences exile and oppression, the other nations erroneously see our suffering as an indication of our abandonment by God, or of the falsehood of our beliefs. But once God's kindness towards us is clearly manifest, all nations will be compelled to recognize Him as Creator, and to recognize Am Yisrael as His treasured people.