It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) sent out a detachment. They took spoils, and among them (the captives) was a man who said to the Companions: I am not one of them (the enemy). I fell in love with a woman and followed her here, so let me look at her, then do whatever seems right to you. There was a tall woman of tawny complexion, and he said to her: O Hubaysh, be safe (accept my greeting) before life comes to an end. Tell me, if I had followed you and caught up with you at Hilyah, or found you at al-Khawaniq, would it not have been right that a lover who endured the hardship of journeying by night and in the heat of midday should attain his desire? She said: Yes, may I be sacrificed for you. So they took him forward and struck off his head. Then the woman came and threw herself upon him, gave one or two gasps, and then died. When they came to the Messenger of Allah (peace and blessings be upon him) they told him the news, and the Messenger of Allah (peace and blessings be upon him) said: "Was there not a single merciful man among you?"
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11985