Sahih Muslim 612
Sahih Muslim · Book 5: The Book of Mosques and Places of Prayer · The times of the five prayers
'Abdullah narrated it on the authority of his father Yahya:
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِيُّ ، قَالَ أَخْبَرَنَا عَبْدُ اللَّهِ بْنُ يَحْيَى بْنِ أَبِي كَثِيرٍ ، قَالَ سَمِعْتُ أَبِي يَقُولُ، لاَ يُسْتَطَاعُ الْعِلْمُ بِرَاحَةِ الْجِسْمِ .
Knowledge cannot be acquired with sloth.