לַמָּ֣ס מֵרֵעֵ֣הוּ חָ֑סֶד וְיִרְאַ֖ת שַׁדַּ֣י יַעֲזֽוֹב׃
Ему, готовому к малейшей доброте, он обязан своему другу, даже тому, кто оставил страх Всемогущего.
Rashi
By one who withholds kindness from his friend Heb. למס, by one who withholds kindness. The “lammed” is a prefix, as in (Num. 26:54), “to the numerous one (לָרַב)”; “to the one who returns (?) (לָשָב),” and (Isa. 28:10, 13) “for a precept (לצו).” מָס too is an expression of a verb, like בָּא, comes: שָב, returns; גָר, dwells; these also are an expression of doing [i.e., the present tense]:
Rashi
who withholds kindness, who destroys it, like (Exod. 16:21), “when the sun grew hot, it melted (ונמס).”