Tehillim 100:2 Midrasch: Midrash Tanchuma

The Holy One, blessed be He, said: In this world My creatures opposed Me, and therefore they were divided into seventy languages because of the evil inclination, but in the world-to-come they will all be of one accord, calling upon My name and serving Me, as it is said: For then will I turn to the peoples one pure language that they may call upon the name of the Lord, to serve Him with one consent (Zeph. 3:9). And He will remove the oppression of idolatrous nations from Israel, and they shall serve Him with gladness, as it is said: Serve the Lord with gladness (Ps. 100:2). However, the nations of the world will serve Him, as is appropriate for them, with trepidation. For example, when a son serves his father, he does so in gladness, saying to himself: If I should commit an error in my father’s presence, he will not be angry with me, for he loves me. Hence he serves him with gladness. However, when a stranger serves a master, he does so with trepidation, saying to himself: If I should commit an error in his presence, he will become angry with me. Therefore, he serves him with trepidation.

Thus, it is written concerning the nations: Why are all the nations in an uproar? And why do the people mutter in vain? (Ps. 2:1). This entire psalm alludes to the nations. For at the conclusion of this psalm, it is written: Serve the Lord with fear, and rejoice with trembling. Do homage in purity, etc. (ibid., vv. 11–12). David said to them: Take heed, lest you deviate from the right path, and He be angry, and ye perish in the way (Ps. 2:12), for He might become angry with you, even over a trivial matter. In reference to Israel, however, it is written: Serve the Lord with gladness; come before His presence with thanksgiving (Ps. 100:2). This psalm was undoubtedly said with reference to Israel, for David composed it in thanksgiving, as it is written: A psalm of thanksgiving (ibid., v. 1).