Musannaf Ibn Abi Shayba 33:234

Waki’ narrated to us, from Ja’far ibn Burqan, from a man whom he would not name, from Umar ibn al-Khattab: That he said in his sermon: "Hold yourselves to account before you are held to account, and weigh yourselves before you are weighed. And adorn yourselves for the Great Presentation, the day you are presented; not a secret of yours shall be hidden."