It was narrated that Abu Sa'eed said:
"The Messenger of Allah said: 'If anyone of you has intercourse with his wife, then he wants to do it again, let him perform ablution.'" (RU)
English reference (RU): Vol. 1, Book 1, Hadith 587 (RU)
Arabic reference (RU): Book 1, Hadith 630 (RU)