Muwatta Malik, Book 28, Hadith 1107 (In-Book) ⓘ

Yahya related to me from Malik that he had heard that Said ibn al-Musayyab said, "When a man comes to his wife in her room, he is believed. When she comes to him in his room, she is believed." Malik commented, "I think that this refers to sexual intercourse. When he comes in to her in her room and she says, 'He has had intercourse with me' and he says, 'I have not touched her', he is believed. When she comes in to him in his room and he says, 'I have not had intercourse with her' and she says, 'He had intercourse with me', she is believed."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ سَعِيدَ بْنَ الْمُسَيَّبِ، كَانَ يَقُولُ إِذَا دَخَلَ الرَّجُلُ بِالْمَرْأَةِ فِي بَيْتِهَا صُدِّقَ الرَّجُلُ عَلَيْهَا وَإِذَا دَخَلَتْ عَلَيْهِ فِي بَيْتِهِ صُدِّقَتْ عَلَيْهِ ‏.‏ قَالَ مَالِكٌ أَرَى ذَلِكَ فِي الْمَسِيسِ إِذَا دَخَلَ عَلَيْهَا فِي بَيْتِهَا فَقَالَتْ قَدْ مَسَّنِي وَقَالَ لَمْ أَمَسَّهَا صُدِّقَ عَلَيْهَا فَإِنْ دَخَلَتْ عَلَيْهِ فِي بَيْتِهِ فَقَالَ لَمْ أَمَسَّهَا وَقَالَتْ قَدْ مَسَّنِي صُدِّقَتْ عَلَيْهِ ‏.‏