אֲנִ֕י הִנֵּ֥ה בְרִיתִ֖י אִתָּ֑ךְ וְהָיִ֕יתָ לְאַ֖ב הֲמ֥וֹן גּוֹיִֽם׃
내가 너와 내 언약을 세우니 너는 열국의 아비가 될지라
Sefer HaChinukh
And they, may their memory be blessed, also said (Mishnah Bikkurim 1:4) about this matter that converts bring them and recite, even though the land was not distributed to them. As it was given to Avraham first, and he was called "the father of many nations" (Genesis 17:4) - meaning to say that anyone who converts is considered like his son.