21:9כ״א:ט׳
1 א

מצחק. לְשׁוֹן עֲ"זָ, כְּמוֹ שֶׁנֶּאֱמַר וַיָּקֻמוּ לְצַחֵק (שמות ל"ב), דָּ"אַ לְשׁוֹן גִּלּוּי עֲרָיוֹת, כְּמָה דְּתֵימָא לְצַחֶק בִּי (בראשית ל"ט), דָּ"אַ לְשׁוֹן רְצִיחָה, כְּמוֹ יָקוּמוּ נָא הַנְּעָרִים וִישַׂחֲקוּ לְפָנֵינוּ וְגוֹ' (שמואל ב ב'), שֶׁהָיָה מֵרִיב עִם יִצְחָק עַל הַיְרֻשָּׁה וְאוֹמֵר אֲנִי בְּכוֹר וְנוֹטֵל פִּי שְׁנַיִם, וְיוֹצְאִים בַּשָּׂדֶה וְנוֹטֵל קַשְׁתּוֹ וְיוֹרֶה בוֹ חִצִּים, כְּמָה דְּתֵימָא כְּמִתְלַהְלֵהַּ הַיֹּרֶה זִקִּים וְגוֹ' וְאָמַר הֲלֹא מְשַׂחֵק אָנִי (משלי כ"ו):

מצחק MAKING SPORT — This means worshipping idols, as it is said in reference of the Golden Calf, (Exodus 32:6) “And they rose up to make merry (לצחק).” Another explanation is that it refers to immoral conduct, just as you say in reference to Potiphar’s wife, (Genesis 39:17) “To mock (לצחק) at me.” Another explanation is that it refers to murder, as (2 Samuel 2:14) “Let the young men, I pray thee, arise and make sport (וישחקו) before us” (where they fought with and killed one another) From Sarah’s reply — “for the son of this bondwoman shall not be heir with my son״ — you may infer that he (Ishmael) was quarrelling with Isaac about the inheritance, saying, “I am the first-born and will, therefore, take a double portion”. They went into the field and he (Ishmael) took his bow and shot arrows at him (Isaac), just as you say (Proverbs 26:18-19) “As a madman who casteth firebrands, [arrows and death] and says: I am only מצחק mocking” (Genesis Rabbah 53:11).