Al-Layth bin Sa’d and others narrated: a man
wrote to Ibn Umar saying: write to me the whole of knowledge. So he wrote to
him: verily, knowledge is abundant, however if you are able to meet Allaah
while your back is free from people’s blood, while your stomach is empty from their
wealth [unlawfully], while your tongue is restrained from their honors and
while sticking to their legion then do so.
Siyar A’laamin-Nubalaa’ 3/222