Augustine of Hippo — as excerpted in the Catena Aurea on John 8:31-36

“(de Verb. Dom. s. xlvii) We have all one Master, and are fellow disciples under Him. Nor because we speak with authority, are we therefore masters; but He is the Master of all, Who dwells in the hearts of all. It is a small thing for the disciple to come to Him in the first instance: he must continue in Him: if we continue not in Him, we shall fall. A little sentence this, but a great work; if ye continue. For what is it to continue in God’s word, but to yield to no temptations? Without labour, the reward would be gratis; if with, then a great reward indeed.”