Acts 2:30

30 But he was a prophet and knew that God had promised him on oath that he would place one of his descendants on his throne.

Read Acts 2:30 Using Other Translations

Therefore being a prophet, and knowing that God had sworn with an oath to him, that of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne;
Being therefore a prophet, and knowing that God had sworn with an oath to him that he would set one of his descendants on his throne,
But he was a prophet, and he knew God had promised with an oath that one of David’s own descendants would sit on his throne.