Monasticism, not prescribed

Then We sent following their footsteps [i.e., traditions] Our messengers and followed [them] with Jesus, the son of Mary, and gave him the Gospel. And We placed in the hearts of those who followed him compassion and mercy and monasticism, which they innovated; We did not prescribe it for them except [that they did so] seeking the approval of Allāh. But they did not observe it with due observance. So We gave the ones who believed among them their reward, but many of them are defiantly disobedient.