Psalm 81

Israel's calendar ran on the moon. Each month began when the new crescent was sighted and reported, and the seventh month opened with a day of trumpet blasts, followed ten days later by the Day of Atonement and then by the week-long harvest feast of booths. The instrument is the shofar, a ram's horn — a signalling instrument with a few notes, used to gather a crowd or an army, not to carry a melody.

I removed his shoulder from the burden, his hands were delivered from the baskets, describes brick work. Egyptian tomb paintings at Thebes show foreign labourers mixing mud with straw, forming bricks in wooden moulds, and carrying them away in baskets slung from a shoulder pole, with overseers standing by. The psalm names the tool a slave would remember.

I proved thee at the waters of strife points back to the water quarrel in the wilderness, where the people demanded water and questioned whether God was among them at all. The festival that celebrated the rescue also named the failure that followed it.

The Jewish traditions preserved in the Mishnah record which psalm the Levites sang in the temple on each day of the week, and this one was the psalm for the fifth day. So it was not only a festival song; it was part of the ordinary weekly round in the courts.