את בנך. אָמַר לוֹ שְׁנֵי בָנִים יֵשׁ לִי, אָמַר לוֹ אֶת יְחִידְךָ; אָמַר לוֹ זֶה יָחִיד לְאִמּוֹ וְזֶה יָחִיד לְאִמּוֹ, אָמַר לוֹ אֲשֶׁר אָהַבְתָּ; אָמַר לוֹ שְׁנֵיהֶם אֲנִי אוֹהֵב, אָמַר לוֹ אֶת יִצְחָק (סנהדרין פ"ט). וְלָמָּה לֹא גִּלָּה לוֹ מִתְּחִלָּה? שֶׁלֹּא לְעַרְבְּבוֹ פִּתְאוֹם וְתָזוּחַ דַּעְתּוֹ עָלָיו וְתִטָּרֵף, וּכְדֵי לְחַבֵּב עָלָיו אֶת הַמִּצְוָה וְלִתֵּן לוֹ שָׂכָר עַל כָּל דִּבּוּר וְדִבּוּר:
את בנך THY SON — Abraham said to God, “I have two sons”. “He answered him, “Thine only son”. Abraham said, “This one is the only son of his mother and the other is the only son of his mother”. God then said, “the one whom thou lovest”. Abraham replied, “I love both of them”. Whereupon God said “even Isaac”. Why did He not disclose this to him at the very first? So as not to confuse him suddenly lest his mind become distracted and bewildered and in his confused state he would involuntarily consent, when there would have been no merit in his sacrifice, and so that he might more highly value God’s command and that God might reward him for the increasing sacrifice demanded by obedience to each and every expression used here (Genesis Rabbah 55:7).