וַיִּשְׁלַ֤ח אַבְרָהָם֙ אֶת־יָד֔וֹ וַיִּקַּ֖ח אֶת־הַֽמַּאֲכֶ֑לֶת לִשְׁחֹ֖ט אֶת־בְּנֽוֹ׃
At iniunat ni Abraham ang kanyang kamay at kinuha ang kutsilyo upang katayin ang kanyang anak.
Rashi
ותכהין HIS EYES WERE DIM through the smoke raised by these women in offering incense to idols (Midrash Tanchuma, Toldot 8). Another explanation is: When Isaac was bound upon the altar and his father was about to slay him, at that very moment the heavens opened, the ministering angels saw it and wept, and their tears flowed and fell upon Isaac’s eyes which thus became dim (Genesis Rabbah 65:10). Another explanation is: They became dim just in order that Jacob might receive the blessings (Genesis Rabbah 65:8).
Or HaChaim
I believe we can explain this verse as being in its proper place. The Torah felt that inasmuch as these Levites had carried out executions with their own hands, something that certainly is not characteristic of righteous people, their image had to be restored. We have learned in Makkot 7 that any court which carries out a death sentence once in seven years (according to some even once in seventy years) is labelled as "a murderous court." In this instance the Levites killed about 3,000 people in a single day. There was a fear that their souls could have been tarnished by the experience seeing that though what they had done was perfectly legal it might leave a residue of mercilessness or a streak of cruelty in their character. In order to reassure both them and the people, Moses the man of G'd, told them to "consecrate their hands." This was not a commandment but a reassurance that by the very act of carrying out the task allocated to them they had consecrated themselves to the service of the Lord. Not only did their action not hint at a character deficiency in them, but, on the contrary, it reflected that they were spiritually very enlightened. The proof was that they did not protest having to sacrifice their own sons or close relatives which put them in a category similar to that of Abraham at the time he was willing to offer up Isaac. G'd testified that Abraham had reached the pinnacle of perfection after he had demonstrated that he had not withheld Isaac (Genesis 22,12). G'd had given Abraham a double blessing at that time (Genesis 22,17). Moses assured the Levites that they too were recipients of a similar blessing by G'd as a reward for what they had done, i.e. ולתת עליכם היום ברכה.
Kaf HaChayim
41) Ibid., And each one must send two portions to his fellow, etc.: In the Binyan Tzion responsa, section 44, he questions whether if one brought the portion himself, and not through a messenger, if he has fulfilled [the commandment]. Since it is written, "and sending," we can say that we need it to be specifically through a messenger, see there. But it appears to me that one cannot be exacting about it only being through a messenger. For behold, we have found the expression, "sending," in several places, and it is not with a messenger. As it is written with Noach (Genesis 8:9), "and he sent out his hand and took it." And with Avraham (Genesis 22:10), "And Avraham sent out his hand." And (Deuteronomy 15:13), "When you send him free from you." And there are many like these. Nevertheless, if it is possible, it should be done with a messenger on account of the honor. But if it is impossible, the commandment should not be negated on account of this. And that is simple.