Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates: A man came to the Prophet (peace and blessings be upon him) and asked about 'azl (withdrawal before ejaculation). The Prophet (peace and blessings be upon him) said: If the fluid from which a child is to be born were poured onto a rock, Allah Almighty would bring a child out of it (the narrator is unsure; perhaps the words are:) a child would come out of it. Whatever soul Allah Almighty is to create, He will certainly create it.
Ahmad and al-Bazzar recorded it, and the chains of both are hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب النكاح / 7573
Hadith Gradingمحدثین:إسنادہ حسن۔
Hadith Takhrij«اخرجه احمد فى المسند (140/3) ، أخرجه مسند أحمد برقم: 12012، وأخرجه البحر الزخار المعروف بمسند البزار 10 - 18 برقم: 7341»