It is narrated from Yahya bin al-Jazzar that Sayyiduna Ibn Mas'ud (may Allah be pleased with him) said: "If I went to my wife at night, then deliberately left off the ritual bath until morning came, that would not keep me from fasting, because I went to her while she was lawful for me."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9535