وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّهُ سَمِعَ سَعِيدَ بْنَ الْمُسَيَّبِ، يَقُولُ لَيْسَ بِرِهَانِ الْخَيْلِ بَأْسٌ إِذَا دَخَلَ فِيهَا مُحَلِّلٌ فَإِنْ سَبَقَ أَخَذَ السَّبَقَ وَإِنْ سُبِقَ لَمْ يَكُنْ عَلَيْهِ شَىْءٌ ‏.‏

Yahya related to me from Malik that Yahya ibn Said heard Said ibnal-Musayyab say, "There is no harm in placing stakes on horses if athird horse enters it. The winner takes the stake, and there is nofine against the loser." Translation Not Available

Book Ref: Muwatta Imam Malik Book 21 Hadith 1006
Web Ref:  Muwatta Imam Malik Book 21 Hadith 46