Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
malik:21-48 – Mālik > Yaḥyá b. Saʿīd > Saʿīd b. al-Musayyab

Yahya related to me from Malik that Yahya ibn Said heard Said ibn al-Musayyab say, "There is no harm in placing stakes on horses if a third horse enters it. The winner takes the stake, and there is no fine against the loser."  

مالك:٢١-٤٨ – 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  

See similar narrations below:

Collected by Bayhaqī
bayhaqi:19772 – Abū Aḥmad ʿAbdullāh b. Muḥammad b. al-Ḥasan al-Mihrajānī > Abū Bakr Muḥammad b. Jaʿfar al-Muzakkī > Muḥammad b. Ibrāhīm al-Būshanjī > Ibn Bukayr > Mālik > Yaḥyá b. Saʿīd > Saʿīd b. al-Musayyib

[Machine] He heard Sa'id ibn al-Musayyib saying, "There is no harm in betting on horses if a gambler is involved. If he wins, he takes the lead, and if he loses, there is no harm upon him."  

البيهقي:١٩٧٧٢ – أَخْبَرَنَا أَبُو أَحْمَدَ عَبْدُ اللهِ بْنُ مُحَمَّدِ بْنِ الْحَسَنِ الْمِهْرَجَانِيُّ أنبأ أَبُو بَكْرٍ مُحَمَّدُ بْنُ جَعْفَرِ الْمُزَكِّي ثنا مُحَمَّدُ بْنُ إِبْرَاهِيمَ الْبُوشَنْجِيُّ ثنا ابْنُ بُكَيْرٍ ثنا مَالِكٌ عَنْ يَحْيَى بْنِ سَعِيدٍ

أَنَّهُ سَمِعَ سَعِيدَ بْنَ الْمُسَيِّبِ يَقُولُ لَيْسَ بِرِهَانِ الْخَيْلِ بَأْسٌ إِذَا أُدْخِلَ فِيهَا مُحَلِّلٌ فَإِنْ سَبَقَ أَخَذَ السَّبْقَ وَإِنْ سُبِقَ لَمْ يَكُنْ عَلَيْهِ شَيْءٌ