مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2119
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Ibn 'Abbas (رضي الله عنه) said: The Messenger of Allah (ﷺ) ordered the one who had intercourse with his wife when she was menstruating to give a dinar or half a dinar in charity,
Musnad Ahmad 2121Saheeh mawqoof]