Four hundred shekels of silver, in negotiable currency (Gen. 23:16)
The Torah foresaw the future difficulties Jews would have defending their rights to their holy sites. The Torah therefore devotes much time detailing the transaction by which Abraham acquired the Cave of Machpela, and the exact sum he spent to purchase it. (Drashot El-Ami)
Who ruled over all that he had (Gen. 24:2)
These words refer to Abraham and indicate just how great a person he was. Though Abraham amassed wealth, he did not become like some other wealthy people for whom money becomes the only motivating factor in their lives. Abraham ruled over his possessions, and not the other way around. (Klai Yakar)
And Isaac went out to meditate in the field (Gen. 24:63)
Rashi explains that the word "meditate" means "to pray--as if pouring forth the contents of one's heart." If such is the case, why didn't the Torah explicitly state that Isaac went out to pray in the field?
We are supposed to take a lesson for our general conduct from the way Isaac prayed. A person should not call attention to himself and publicly announce his fear of Heaven. Rather, we should conduct ourselves as Isaac did--quietly, and without fanfare. A passer-by would have thought that Isaac was only strolling in the field, when in reality he was composing the afternoon prayer. (Leket Amarim)
And Abraham was old, well on in days (Gen. 24:1)
In Hebrew, the phrase "well on in days" is "ba bayamim"--literally, "he had come with his days." Abraham's life was full, and he utilized every day to the fullest; he did not waste even one day.
A hint as to how we can achieve this ourselves is found in the letters of the word "bayamim"--"ba" and "yamim." "Ba" (spelled with a bait in Hebrew) means two. Abraham always had the image of two distinct days in his mind--the day of birth and the day of death. We must keep in mind why we are born and the fact that we will ultimately be accountable for our deeds after we die. (Divrei Tzadikim)