Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates from Sayyiduna Umar (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) forbade 'azl with a free woman except with her permission.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14324