Avraham negotiates and (over)pays for the plot of land in which he will bury his wife (23:1-16). It is noteworthy that Avraham never questions G-d’s promise that the land he’s buying is in fact his. According to the Midrash, the Akeida (binding of Yitzchak) is G-d’s tenth and final test for Avraham. Why isn’t this (need to purchase land that was already promised to him) counted as another of Avraham’s tests?
Rav Shimon Schwab proposes that Avraham had reached a level of acceptance such that he would never question events in his life. This inner peace and understanding that whatever happens is part of G-d’s plan for him meant that no obstacles or hardships would be too challenging to accept or overcome. Life happens just as it’s meant to happen, and this acceptance brought an unwavering inner peace to Avraham, and it should do the same for us all.