Hebrews 7 21
But he became a priest with an oath because God told him, “The Lord has taken a solemn vow and will not change his mind: You are a priest forever.”
Compare with other 3 random translations
ASV Hebrews 7:21(for they indeed have been made priests without an oath; but he with an oath by him that saith of him, The Lord sware and will not repent himself, Thou art a priest for ever);
YLT Hebrews 7:21and he with an oath through Him who is saying unto him, 'The Lord sware, and will not repent, Thou art a priest — to the age, according to the order of Melchisedek;')
GNV Hebrews 7:21But this is made with an othe by him that said vnto him, The Lord hath sworne, and will not repent, Thou art a Priest for euer, after the order of Melchi-sedec)