John Chrysostom — as excerpted in the Catena Aurea on John 1:47-51

“(Hom. xx) That our Lord then had this knowledge, had penetrated into his mind, had not blamed but praised his hesitation, proved to Nathanael that He was the true Christ: Nathanael answered and saith unto Him, Rabbi, Thou art the Son of God, Thou art the King of Israel: as if he said, Thou art He who was expected, thou art He who was sought for. Sure proof being obtained, he proceeds to make confession; herein shewing his devotion, as his former hesitation had shewn his diligence.”