It is narrated from Sa'id bin al-Musayyib (may Allah have mercy on him) and 'Ubaydullah bin 'Abdullah bin 'Utbah (may Allah have mercy on him) that the Prophet (ﷺ) said: "If she gives birth to a red and straight-haired child, then he is her husband's, and if she gives birth to a black, dark child, then he is the one about whom suspicion has been raised." He said: Then she gave birth to a black, dark child.
Hadith Referenceمسند الإمام الشافعي / كتاب اللعان / 1332
Hadith Takhrijاسناده ضعيف لإرساله اخرجه البيهقي في المعرفة السنن والآثار (4558)۔