Musnad Abu Ya'la al-Mawsili 1:67

Abu Khaythama narrated to us, 'Amr ibn 'Asim al-Kilabi narrated to us, Sulayman ibn al-Mughirah narrated to us, from Thabit, from Anas, who said: Abu Bakr said after the death of the Messenger of Allah (may Allah bless him and grant him peace) to 'Umar: "Come with us to Umm Ayman, that we may visit her as the Messenger of Allah (may Allah bless him and grant him peace) used to visit her." When we reached her, she wept. They both said to her: "What makes you weep? What is with Allah is better for His Messenger." She said: "I do not weep because I do not know that what is with Allah is better for His Messenger, but I weep because the revelation from the heaven has ceased." He said: "So she stirred them to weep, and they began to weep with her."