Exodus 29:39

The one lamb thou shalt offer in the morning; and the other lamb thou shalt offer at even:

Ver. 39. Thou shalt offer in the morning.] These two lambs were types of the Lamb of God, taking away the sins of the world, with a commemoration of whose benefits the day was begun and ended. Wherefore, also, from David's days and forwards, they sang the 22nd Psalm at the morning sacrifice, and the 136th Psalm at the evening.