مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2310
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
The Messenger of Allah (ﷺ) said: “He is not one of us who has intercourse with a pregnant woman [i.e., a female prisoner of war who is pregnant]."
Musnad Ahmad 2318Saheeh because of corroborating evidence; its isnad is da’ee