Sefer HaBahir 78
1[The students asked,] "From where is it that Abraham had a daughter?" [Rabbi Rachumai responded,] "As it is written, 'YHVH blessed Abraham with everything [בכל]' (Genesis 24:1), and it is written, 'All who are called by My name and who, for My Glory, I created, I formed him, indeed, I made him' (Isaiah 43:7)." [They asked,] "Was this blessing his daughter or not?"[He replied,] "Yes, she was his daughter. A parable to which it can be compared: to a king that had a servant, perfect and complete, before him. He tested him with many tests, and he withstood all of them. The king said, 'What will I give to this servant, and what will I do for him?' He said, 'I do not have anything, but I will command my older brother to advise, protect, and honor him.' The servant returned with his his older brother and learned his traits. The brother loved him greatly and called him his love, as is written, 'The seed of Abraham, my beloved' (Isaiah 41:8). He said, 'What will I give to him, and what will I do for him?' Behold, I have made a beautiful vessel, and in it is a beautiful pearl. There is nothing like them amongst kings' treasures. I will give it to him and he will be worthy in his place, as is written, 'YHVH blessed Abraham with everything [בכל]' (Genesis 24:1)."
source: Sefaria Community Translation