Midrash sa Genesis 13:7: Pesikta Rabbati, Mekhilta DeRabbi Yishmael, Midrash Tanchuma & Aggadat Bereshit

... [What about all] the praise of Joseph, who exceeded in the honor of his father? And yet he did not enter into him all the time, such that were it not that they came to tell him, "Your father is sick," he would not have known! Rather this is to inform you of his righteousness. For he did not want to be alone with his father, lest he say to him, "How did your brothers act with you?" And [then] he would curse them.... Hence he did not go to his father all the time.)

They said: Now they are coming to rekindle the strife between our father and theirs, viz.(Genesis 13:7) "And there was strife between the herdsmen of Avram's cattle and those of Lot's, etc."

Prior to the verse After these things scripture states: And Abraham heard that his brother was taken captive (Gen. 14:14). Was Lot actually Abraham’s brother? No, indeed! This statement is simply proof of Abraham’s humility. Though Abraham and Lot had quarreled, as it is written: And there was a strife between the herdsmen of Abraham’s cattle and the herdsmen of Lot’s cattle (ibid. 13:7), he called him brother nevertheless, as it is said: For we are brethren (ibid., v. 8). And he led forth (va-yarek) his trained men (Gen. 14:14). This verse indicates that he covered his men with silver and gold. Then he said to them: “Know that we are about to do battle; do not covet their silver and gold, for all this will be yours.” Va-yarek is employed in Scripture only in reference to gold, as it is said: The wings of a dove are all covered with silver, and her pinions with the shimmer of gold (yerakrak) (Ps. 68:14).