Sabr is patience, endurance, steadfastness under what one does not choose. Its root occurs roughly a hundred times in the Qur'an, which makes it one of the most insistently commanded of all the virtues: "seek help through patience and prayer" (2:45, 2:153), "God is with the patient", "the patient will be given their reward without measure" (39:10).
Moral writers analyse it into kinds. Al-Ghazali, who devotes a book of the Ihya to patience and gratitude together, distinguishes patience in carrying out what is commanded, patience in abstaining from what is forbidden, and patience under affliction, and treats the first two as harder because they are continuous. The tradition pairs sabr with shukr as the two halves of faith, gratitude the response to ease, patience the response to hardship, so that between them they cover every condition a person can be in.
Its exemplars are prophets. Job, Ayyub, is the standing type of endurance under affliction (21:83-84, 38:41-44), and Jacob, told of the loss of Joseph, answers with sabr jamil, beautiful patience (12:18, 12:83), a phrase that became a formula of condolence. The tradition is explicit that this is not passivity: sabr is repeatedly coupled with striving, with the command to enjoin right, and with the proverb that one ties the camel and then trusts in God. In modern usage the word carries into ordinary speech, said at funerals and in difficulty, and it remains among the most widely recognised religious terms in the Muslim world.