Fadalah bin 'Ubaid (May Allah be pleased with him) reported:
When Messenger of Allah (ﷺ) led Salat, some people would fall down from their standing posture out of extreme hunger. They were of the people of As-Suffah. The nomad Arabs would say that they were insane. After concluding Salat, Messenger of Allah (ﷺ) would turn to them and say, "If you were to know what is in store for you with Allah, the Exalted, you would wish to augment your starvation and lack of provisions."[At-Tirmidhi].
Arabic/English book reference: Book 1, Hadith 515