Uthman was absent from Badr only because his wife, the daughter of the Messenger of Allah ﷺ, was ill. The Prophet ﷺ said to him, "You will have the reward of one who was present at Badr, along with his share of the spoils."
حدثنا موسى حدثنا أبو عوانة حدثنا عثمان بن موهب
إنما تغيب عثمان عن بدر فإنه كانت تحته بنت رسول الله ﷺ وكانت مريضة فقال له النبي ﷺ إن لك أجر رجل ممن شهد بدرا وسهمه