(19) باب صَلاَةُ الأَوَّابِينَ حِينَ تَرْمَضُ الْفِصَالُ
Zaid b. Arqam reported that the Messenger of Allah (ﷺ) went out to the people of Quba' and saw them observing prayer; upon this he said:
The prayer of the penitent should be observed when the young weaned camels feel heat of the sun.
Reference: Sahih Muslim 748 b
In-book reference: Book 6, Hadith 176
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1631