“Every person’s worth is what they do well.”

Ibn ‘Abd al-Barr (d. 463 AH / 1071 CE) reports that ‘Ali said this in a sermon, in the form “people are the children of what they do well, and each person’s measure is what he does well — so speak with knowledge, and your measures will show.” He adds that the scholars said no sentence urges the pursuit of knowledge more than this one. He gives it without a connected chain, so it is ‘Ali’s as the scholars have long quoted it, rather than an established report.