From the Retractations, ii. 21: To write the Book on the Work of Monks, the need which compelled me was this. When at Carthage there had begun to be monasteries, some maintained themselves by their own hands, obeying the Apostle; but others wished so to live on the oblations of the faithful, that doing no work whence they might either have or supply the necessaries of life, they thought and boasted that they did rather fulfill the precept of the Gospel, where the Lord says, Behold the fowls of heaven, and the lilies of the field,. Whence also among laics of inferior purpose, but yet fervent in zeal, there had begun to arise tumultuous contests, whereby the Church was troubled, some defending the one, others the other part. Add to this, that some of them who were for not working, wore their hair long. Whence contentions between those who reprehended and those who justified the practice, were, according to their party affections, increased. On these accounts the venerable old Aurelius, Bishop of the Church of the same city, desired me to write somewhat of this matter; and I did so. This Book begins, “Jussioni tuæ, sancte frater Aureli.”
This work is placed in the Retractations next after that “On the Good of Marriage” which belongs to the year 401.
Source: On the Work of Monks (New Advent)