Musannaf Ibn Abi Shaybah 12499 — Those who permitted weeping over

It is narrated from Sayyiduna Usamah bin Zayd (may Allah be pleased with him) that when the daughter of Sayyidah Zaynab (may Allah be pleased with her) was brought to the Prophet (peace and blessings be upon him), tears came to his eyes. The child's breath was rattling, as though it were in an old dry waterskin. Seeing this condition, he (peace and blessings be upon him) wept. A man said: "O Messenger of Allah (peace and blessings be upon him)! You are weeping when you have forbidden weeping?" He (peace and blessings be upon him) said: "This is only mercy (these are tears of mercy) which Allah Almighty has placed in the hearts of His servants, and Allah, the Exalted, has mercy only on those of His servants who are merciful."