(1)ה׳ appeared to him by the terebinths of Mamre; he was sitting at the entrance of the tent as the day grew hot. (2) Looking up, he saw three figures standing near him. Perceiving this, he ran from the entrance of the tent to greet them and, bowing to the ground, (3) he said, “My lords! If it please you, do not go on past your servant.

The reason Abraham addressed only Michael was that he felt that the other two were going to come to him even without a specific invitation, seeing that G'd had despatched them with messages for him. One was meant to cure him, the other to inform him of the impending birth of Isaac. The same did not apply to the third angel Gabriel, whose function it was to destroy Sodom. He had no task to perform in Abraham's home. This is why Abraham appealed to him not to depart until he had partaken of his hospitality. Gabriel consented.

(2) The reward one receives for accompanying guests is greater than all of the others. This is a statute which Abraham our Patriarch instituted and the path of kindness which he would follow. He would feed wayfarers, provide them with drink, and accompany them. Showing hospitality for guests surpasses receiving the Divine Presence as Genesis 18:3 states: "And he saw and behold there were three people."
Accompanying them is greater than showing them hospitality. Our Sages said: "Whoever does not accompany them is considered as if he shed blood."

(3) We compel people to accompany wayfarers in the same manner as we compel them to give charity. The court would prepare agents to accompany people who travel from place to place. If they were lax in this matter, it is considered as if they shed blood. Even a person who accompanies a colleague for four cubits will receive a great reward.
What is the extent to which a person must accompany a colleague? A teacher must accompany his student to the outskirts of the city. A person must accompany a colleague to the city's Sabbath limits. A student must accompany his teacher for a parsah. If he was his master teacher, he must accompany him until three parseot.

We know already from Genesis 18,16 where Avraham escorted the angels who had visited him, that he was in the habit of escorting his guests. This last stage in fulfilling the commandment of being hospitable is in fact the part for which the host receives his true reward. We find, for instance, that immediately after Avraham had escorted the angels away from his house, G’d rewarded him by revealing to him the impending fate of Sodom and giving him a chance to plead for their lives. We find something similar in Psalms 135,4 where the psalmist wrote כי יעקב בחר לו י-ה, and the reading of the last two words is one word, i.e. לויה, suggesting that the reason G’d chose Yaakov as His people was because they practice the virtue of escorting their guests. We find that the Torah also provides a hint of this when relating the journey of Eliezer to get a bride for Yitzchak. In Genesis 24,56 Eliezer is quoted as saying to his hosts: אל תאחרו אותי וה׳ הצליח דרכי, “do not delay me seeing that G’d has made my mission successful.” (The respective last letters in the words spell אל תאחרו אותי וה-י-ה-ו-ה spell the word לויה, “escort.)”

To David: Do not compete with evildoers. As it says in Proverbs 23:17, "Do not let your heart envy sinners, but always be zealous for the fear of the Lord." So why envy (them) in the fear of the Lord all day long? Do not envy the candle of the wicked, for you can see how much oil is in it, a quarter or an eighth, (yet) the entire oil (burns) and the candle goes out. And thus it says (in the same chapter, verse 18), "Surely there is a future hope for you, and your hope will not be cut off." And it says (verse 20), "The lamp of the wicked is snuffed out." This is its bright rule. Therefore, David says, "Do not compete with evildoers." Be zealous for a candle that never goes out, and whose candle does not go out. As it says (Proverbs 6:23), "For this command is a lamp, this teaching is a light, and correction and instruction are the way to life." Therefore, do not let your heart envy (them). The Lord said, "I am jealous because if there were no jealousy, the world would not exist. For if Abraham had not been jealous for the Lord, he would not have acquired heaven and earth." And when did he become jealous? When he said to the kings of righteousness, "How did you come out of the ark?" He said to him, "With righteousness that we did." He said to him, "What righteousness did you have to do, and were there poor people there? There was only Noah and his sons, so for whom did you do righteousness?" He said to him, "About the animals and the birds." We were not sleeping all night, but we were giving (food) to this one and to that one. Once we delayed ourselves and my father was injured. At that moment, Abraham said, "If these (people) had not done righteousness with animals, birds, and beasts, they would not have come out of there. And because he delayed himself, he almost received his reward and was injured. If I do (good) with human beings, who are in the image and likeness of angels, how much more will I benefit from the harm?" Immediately (Genesis 21:33), he planted a tamarisk tree. He ate, drank, and rejoiced. And Solomon said (Ecclesiastes 4:4), "And I saw that all toil and all achievement spring from one person's envy of another. This too is meaningless, a chasing after the wind." Therefore, do not let your heart envy (them) in sin....

For I have singled him out, that he may instruct his children and his posterity to keep the way of ה׳ by doing what is just and right, in order that ה׳ may bring about for Abraham what has been promised him.”

FOR I HAVE KNOWN HIM (‘YEDATIV’), TO THE END (‘LEMA’AN’) THAT HE MAY COMMAND HIS CHILDREN. Rashi comments: “For I have known him, as the Targum takes it, is an expression denoting affection, just as A kinsman (‘moda’) of her husband’s;And I know thee. Still the main connotation of all these expressions is that of knowing, for he who holds a person in affection and draws him to himself knows him well and is familiar with him. But if you explain it as the Targum does — i.e., “I know that he will command his children” — then the word lema’an (to the end) does not fit into the sense.”
It is possible that the word yedativ means “I have raised him and elevated him so that he shall command his children after him to do that which is right before Me, and therefore I will make him a great and mighty nation so that he should serve Me. In a similar sense are the verses: I know thee (‘yedaticha’) by name;What is man, that Thou knowest htm? Or the verse may be stating, I know that he will command, and in a similar sense is the verse, So that thine ox and thine ass may have rest (lema’an yanuach), meaning that he may have rest.
The correct interpretation appears to me to be that the word yedativ literally means “knowing.” He is thus alluding that G-d’s knowledge, which is synonymous with His Providence in the lower world, is to guard the species, and even the children of men are subject despite it to the circumstantial evil occurrences until the time of their visitation comes. But as regards His pious, He directs His Providence to know each one individually so that His watch constantly attaches to him, His knowledge and remembrance of him never departs, as it says: He withdraweth not His eyes from the righteous. There are many verses on this theme, as it is written, Behold, the eye of the Eternal is toward them that fear Him, and other verses besides.