At even - See Exodus 12:6.

One lamb thou shalt offer in the morning - These two lambs, one in the morning, and the other in the evening, were generally termed the morning and evening daily sacrifices, and were offered from the time of their settlement in the promised land to the destruction of Jerusalem by the Romans. The use of these sacrifices according to the Jews was this: "The morning sacrifice made atonement for the sins committed in the night, and the evening sacrifice expiated the sins committed during the day."

The one lamb thou shalt offer in the morning,.... And before this no other sacrifice was to be offered, and therefore it was slain and offered very early; and yet it was not lawful to slay it before break of day, wherefore great care was taken that it should not;"he that was appointed over the service used to say to the priests, go out, and see if the time of slaying is come; if it is come, he that went out to see, said, coruscations or brightnesses; Matthias the son of Samuel said, does it enlighten the face of the whole east as far as Hebron? he said, yes; why was this necessary? because one time the light of the moon ascended, and they thought the east was enlightened (or it was break of day), and they slew the sacrifice (h):"
and the other lamb thou shalt offer at even, or
between the two evenings; of which phrase See Gill on Exodus 12:6 Josephus (i) says, it was about the ninth hour, or three o'clock in the afternoon, that the daily sacrifice was offered: the Misnic doctors say (k), it was slain at eight and a half, or half an hour after two o'clock, and was offered up at nine and a half, or half an hour after three o'clock: they stayed as long as they could before they offered it, because no sacrifice was offered after it but the passover. We are told that the lamb of the morning was slain in the northwest corner of the altar, and that of the evening in the northeast corner (l): the reason of this was, because in the morning the sun was in the east, and shone over against the west; but the evening daily sacrifice was when the sun was in the west, and shone opposite the east (m): this was in a good measure literally fulfilled in Christ, namely, as to the time of slaying and offering the daily sacrifice; for he was crucified at the third hour, that is, at nine o'clock in the morning, at the sixth hour, or at twelve o'clock at noon, darkness was upon the earth, which continued till the ninth, and then he gave up the ghost, which was three o'clock in the afternoon, the usual time of slaying and offering the daily evening sacrifice, Mark 15:25 and this may signify the extensiveness of Christ's sacrifice, reaching from the morning of the world to the evening of it. He was slain and offered up in the morning of the world, in the purpose and promise of God, in the typical sacrifices of men, and in the faith of his people, who looked to him as the atoning Saviour, and in the efficacy of his blood, which reached to all the saints from the beginning, for the pardon and atonement of their sins; and it was at the end or evening of the Jewish world and state that Christ was offered up a sacrifice for sin, and the virtue of it will continue to the end of the world. Christ is the Lamb of God that continues to take away the sin of the world, and his blood continues to cleanse from all sin, and he ever lives to make intercession for transgressors. Good men are continually sinning, and they ever stand in need of the application of pardoning grace and mercy; there are sins of the night, and the sins of the day they fall into, and nothing can expiate them but the blood and sacrifice of Christ. The repetition of these sacrifices every day, morning and night, shows that they could not really and perfectly take away sin; the cessation of them was a token of perfect atonement by Christ, which made them needless and useless: and this may teach us, that the sacrifices of prayer and praise should be morning and evening; in the morning we should express our thankfulness for the mercies of the night, and pray for the continuance of them the day following; and at the evening we should offer up the sacrifices of praise for the mercies of the day, and pray for the mercies of the night; and at both seasons should be concerned to have a fresh application of the atoning blood and sacrifice of Christ, for the taking away from us the sins of the night and day.
(h) Misn. Yoma, c. 3. sect. 1, 2. Tamid, c. 3. sect. 2. (i) Joseph. Antiqu. l. 14. c. 4. sect. 3. (k) Misn. Pesachim, c. 5. sect. 1. (l) Misn. Tamid, c. 4. sect. 1. (m) Bartenora in Misn. Tamid, c. 4. sect. 1.