It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) used to have intercourse with his wives and perform ghusl (ritual bath) only once. Imam Abu Bakr (may Allah have mercy on him) says that this hadith is ghareeb (rare). In the well-known chain, Ma'mar narrates from Qatadah.