Psalm 81
Psa 81:1-16. Gittith - (See on Psa 8:1, title). A festal Psalm, probably for the Passover (compare Mat 26:30), in which, after an exhortation to praise God, He is introduced, reminding Israel of their obligations, chiding their neglect, and depicting the happy results of obedience.
our strength - (Psa 38:7).

unites the most joyful kinds of music, vocal and instrumental.

the new moon - or the month.
the time appointed - (Compare Pro 7:20).

a testimony - The feasts, especially the Passover, attested God's relation to His people.
Joseph - for Israel (Psa 80:1).
went out through - or, "over," that is, Israel in the exodus.
I heard - change of person. The writer speaks for the nation.
language - literally, "lip" (Psa 14:1). An aggravation or element of their distress that their oppressors were foreigners (Deu 28:49).

God's language alludes to the burdensome slavery of the Israelites.

secret place - the cloud from which He troubled the Egyptians (Exo 14:24).
proved thee - (Psa 7:10; Psa 17:3) - tested their faith by the miracle.

(Compare Psa 50:7). The reproof follows to Psa 81:12.
if thou wilt hearken - He then propounds the terms of His covenant: they should worship Him alone, who (Psa 81:10) had delivered them, and would still confer all needed blessings.

11 They failed, and He gave them up to their own desires and hardness of heart (Deu 29:18; Pro 1:30; Rom 11:25).

13 Obedience would have secured all promised blessings and the subjection of foes. In this passage, "should have," "would have," etc., are better, "should" and "would" expressing God's intention at the time, that is, when they left Egypt.