Musannaf Ibn Abi Shayba 21:396

Husayn ibn Ali narrated to us, from Tu'mah ibn Abdullah, from a man called Mika'il, an elder from the people of Khurasan, who said: When Umar would stand at night, he would say: "You see my station and You know my need, so return me from You, O Allah, with my need fulfilled, successful, having my prayer answered, and having it accepted for me, while You have forgiven me and had mercy upon me." When he finished his prayer, he would say: "O Allah, I do not see anything of the world that lasts, and I do not see any state in it that remains upright. O Allah, make me move within it with knowledge and remain silent with wisdom. O Allah, do not increase the world for me so that I become arrogant, and do not decrease it for me so that I forget, for indeed, that which is little and suffices is better than that which is much and distracts."