He asked life of you, and you gave it to him, even length of days forever and ever.
All Commentaries on Psalms 21:4 Go To Psalms 21
Augustine of Hippo
AD 430
5. "He asked life; and Thou gavest Him:" He asked a resurrection, saying, "Father, glorify Thy Son;" and Thou gavest it Him, "Length of days for ever and ever" (ver. 4). The prolonged ages of this world which the Church was to have, and after them an eternity, world without end.