It is reported that Al-Zuhrī – Allāh have mercy on him – said to Yūnus b. Yazīd:

O Yūnus! Do not try to overcome knowledge, for verily knowledge is [like vast] valleys: whichever of them you take will stop you before you traverse it. Instead, take it over the days and nights. And do not take knowledge all at once, for whoever tries to take it all at once will lose it all at once. Rather take it bit by bit over the days and nights.

Ibn ʿAbd Al-Barr, Jāmiʿ Bayān Al-ʿIlm article 652.