Lord Jesus
Lord — Master and rightful ruler; in Paul's letters the title of the risen Jesus, carrying the weight of the divine name
Furthermore then we beseech you, brethren, and exhort you by the Lord Jesus, that as ye have received of us how ye ought to walk and to please God, so ye would abound more and more. 1 Thessalonians 4:1–2
Paul's counsel carries the authority of the Lord Jesus; his commandments were given by Him.
How we know: the verse itself names Him
