From Sahih Bukhari (Hadith 4567):
Narrated Abu Sa`id Al-Khudri:During the lifetime of Allah's Messenger (ﷺ), some men among the hypocrites used to remain behind him (i.e. did not accompany him) when he went out for a Ghazwa and they would be pleased to stay at home behind Allah's Messenger (ﷺ) When Allah's Messenger (ﷺ) returned (from the battle) they would put forward (false) excuses and take oaths, wishing to be praised for what they had not done. So there was revealed:-- "Think not that those who rejoice in what they have done, and love to be praised for what they have not done
Reference: Bukhari 4567