Musnad Ahmad 941:37

Abu Mu'awiyah narrated to us, 'Asim narrated to us, from Abu 'Uthman al-Nahdi, from Usamah ibn Zayd, who said: The Messenger of Allah (peace and blessings of Allah be upon him) was brought Umaymah, the daughter of Zaynab, while her soul was rattling as if she were in a water skin. The Messenger of Allah (peace and blessings of Allah be upon him) said: "To Allah belongs what He took, and to Allah belongs what He gave, and everything has a specified term." His eyes shed tears. Sa'd ibn 'Ubadah said to him: "O Messenger of Allah, do you weep? Did you not forbid weeping?" The Messenger of Allah (peace and blessings of Allah be upon him) said: "It is only a mercy that Allah has placed in the hearts of His servants, and Allah only shows mercy to the merciful among His servants."