Nafi' (may Allah have mercy on him) said: Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) used to beat his sons for practising 'azl, that is, he forbade it. But Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) and Abdullah bin Mas'ud (may Allah be pleased with him) both regarded 'azl as disliked, and its permissibility is also reported from them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14329