Hadith 8:104
Anas said that a man of Kilab asked the Prophet about hiring a stallion to cover a female and he forbade him; but when he said, "Messenger of God, we lend a stallion to cover a female and are given a present," he gave him licence to accept a present. Tirmidhi transmitted it.
وَعَنْ أَنَسٍ: أَنَّ رَجُلًا مِنْ كِلَابٍ سَأَلَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنْ عَسْبِ الْفَحْلِ فَنَهَاهُ فَقَالَ: يَا رَسُولَ اللَّهِ إِنَّا نُطْرِقُ الْفَحْلَ فَنُكْرَمُ فَرَخَّصَ لَهُ فِي الْكَرَامَةِ. رَوَاهُ التِّرْمِذِيّ
Original Reference: Mishkat al-Masabih 2866