Usamah bin Zaid said: "The son of one of the daughters of the Messenger of Allah P.B.U.H was dying. She sent for him, asking him to come to her, and he sent word to her, saying: 'To Allah Him belongs what He has given. Everything has an appointed time with Him, so be patient and seek reward.' But she sent for him again, adjuring him to come. So the Messenger of Allah P.B.U.H got up. and I got up with him, as did Mu'adh bin Jabal, Ubayy bin Ka'b and 'Ubadah bin Samit. When we entered they handed the child to the Messenger of Allah P.B.U.H, and his soul was rattling in his chest." I think he said that it was like a water skin. "The Messenger of Allah P.B.U.H wept, and 'Ubadah bin Samit said to him: 'What is this, 0 Messenger of Allah?' He said: 'It is the compassion which Allah has created in the son of Adam.Allah only shows mercy to those of His slaves who are compassionate.''' (Sahih)