In contrast with the stability and eternity of God, Moses directs our attention next to the weakness of man and to the brevity of his earthly life (vv. 3-6). In the dry, arid climate of the near east a night rain will often cause a carpet of green grass to spring up in the morning on the otherwise brown hills. But the blazing daytime sun will frequently also scorch it out by nightfall. Moses is saying that our lives are like that.

We come now to Psalm 90 itself, a psalm that, like Numbers 20, is a reflection on human mortality and the brevity of life, plus quiet confidence in God who is the steadfast hope of the righteous. This psalm is probably the greatest passage in the Bible contrasting the grandeur of God with man's frailty.

Psalm 90 is the only psalm in the Psalter that is attributed to Moses, but it is not the only piece of poetry Moses wrote. There are two other "songs of Moses" in the Bible. One of them was the hymn the Jews sang after their deliverance from Egypt and the drowning of Pharaoh and his army in the Red Sea (Exod. 15:1-18). The other was the song Moses recited to the people before his ascension of Mount Nebo, where he died (Deut. 32:1-43). The first song is pure praise, a joyful celebration. The second is a reminder of Israel's past rebellion against God and of God's resulting judgments. Psalm 90, the song we are to study now, is the most sober and also the most personal of these poetic compositions.

Do you remember the cry of the saints in Revelation, which I referred to previously: "How long, Sovereign Lord" (Rev. 6:10)? That question hangs in the air throughout Revelation. It is there at the end. But at the end we also have the answer of Jesus, who says, "Behold, I am coming soon! My reward is with me, and I will give to everyone according to what he has done. I am the Alpha and the Omega, the First and the Last, the Beginning and the End" (Rev. 22:12, 13; see vv. 7, 20). To this we reply, “Amen. Come, Lord Jesus" (v. 20). The editor who closed out this third book of the Psalter had a like faith when he followed Ethan's cry with the faith-filled ascription: "Praise be to the LORD forever! Amen and Amen” (Ps. 89:52).

We also are party to a covenant, if we have believed on Jesus Christ. The Jews are to be brought to faith in the last days. But we stand in a like covenant today, and the attributes of God that formed the earlier covenant are for our encouragement. When we talk about God's irrevocable covenant we are speaking about God's immutability. Immutability means that God does not change, and because he does not change he can be counted on.