When it was the day (of the battle) of Badr, prisoners of war were brought including Al-Abbas who was undressed. The Prophet (ﷺ) looked for a shirt for him. It was found that the shirt of `Abdullah bin Ubai would do, so the Prophet (ﷺ) let him wear it. That was the reason why the Prophet (ﷺ) took off and gave his own shirt to `Abdullah. (The narrator adds, “He had done the Prophet (ﷺ) some favor for which the Prophet liked to reward him.”)