Psalms 88:36

Wherefore also in the 89th Psalm, of which the title is, “An instruction for himself by Ethan the Israelite,” mention is made of the promises God made to king David, and some things are there added similar to those found in the Book of Samuel, such as this, “I have sworn to David my servant that I will prepare his seed for ever.” And again, “Then thou spakest in vision to thy sons, and saidst, I have laid help upon the mighty One, and have exalted the chosen One out of my people. I have found David my servant, and with my holy oil I have anointed him. For mine hand shall help him, and mine arm shall strengthen him. The enemy shall not prevail against him, and the son of iniquity shall harm him no more. And I will beat down his foes from before his face, and those that hate him will I put to flight. And my truth and my mercy shall be with him, and in my name shall his horn be exalted. …

32. Listen for thy confirmation in hope, for thy security, if thou knowest thyself to be among the members of Christ. “I have sworn once by My holiness that I will not lie unto David” ( ver. 35 ). Dost thou wait till God swear a second time? How often is He to swear, if in one oath He is false? One oath He made for our life, who sent His Only One to die for us. “I have sworn once by My holiness, that I will not lie unto David.” “His seed shall endure for ever” ( ver. 36 ). His seed endures for ever; because the Lord knows them that are His. “And His seat is like as the sun before me:” “and as the moon perfect for evermore: and the faithful witness in heaven” ( ver. 37 ). They are His seat, in whom He sits and reigns. But if His seat, His members also; because even our members are the seat of our head. …

Orth. Go on then to what follows and your opinion upon this point will be in every way confirmed, for again saith the God of the universe, “Once have I sworn by my holiness, if I lie unto David, his seed shall endure for ever and his throne as the sun before me. It shall be established for ever as the moon.”

23. We know then for certain that the Lord was to be born of a Virgin, but we have to shew of what family the Virgin was. The Lord sware in truth unto David, and will not set it aside. Of the fruit of body will I set upon thy throne : and again, seed will I establish for ever, and his throne as the days of heaven . And afterwards, Once have I sworn by My holiness that I will not lie unto David. His seed shall endure for ever, and his throne as the sun before Me, and as the moon established for ever . Thou seest that the discourse is of Christ, not of Solomon. For Solomon’s throne endured not as the sun. But if any deny this, because Christ sat not on David’s throne of wood, we will bring forward that saying, The Scribes and the Pharisees sit in Moses’ seat : for it signifies not his wooden seat, but the authority of his teaching. …

Concerning the holy and much-lauded ever-virgin one, Mary, the Mother of God, we have said something in the preceding chapters, bringing forward what was most opportune, viz., that strictly and truly she is and is called the Mother of God. Now let us fill up the blanks. For she being pre-ordained by the eternal prescient counsel of God and imaged forth and proclaimed in diverse images and discourses of the prophets through the Holy Spirit, sprang at the pre-determined time from the root of David, according to the promises that were made to him. For the Lord hath sworn, He saith in truth to David, He will not turn from it: of the fruit of Thy body will I set upon Thy throne . And again, Once have I sworn by My holiness, that I will not lie unto David. His seed shall endure for ever, and His throne as the sun before Me. …