Ibn Ezra

Let us break their cords (nenattekah et mosroteimo): [The word mosroteimo - their cords/bonds] is from the root musar (מוּסָר - discipline, bond, instruction). Also their ropes (גַּם עֲבֹתֵימוֹ - gam avoteimo): Means thick ropes (chavalim avotim). The meaning [of mosrot and avot] is one and the same, [expressed] with different words. For this is a manner of rhetorical elegance (derekh tzachut), like [in (Numbers 23:8)]: "How shall I curse (mah ekov)... and how shall I denounce (umah ez'om)." [Using synonyms in parallel clauses]. He who sits (יוֹשֵׁב - yoshev) [referring to yoshev ba-shamayim - "He who sits in the heavens" in v. 4]: Because Scripture mentioned [in v. 2] "kings of the earth take their stand" (yityatzvu malkhei eretz), it states, in contrast to them, "He who sits in the heavens," which are above man. The [Rav Saadia] Gaon said: That the meaning of He will laugh (יִשְׂחָק - yischak) [v. 4] is that He will make them into an object of laughter and derision (sechok u-la'ag). And the correct [view] is: That HaShem created substance/matter (ha-geshem), which is the essence, and the forms (ha-tzurot), which are accidents/attributes. [These philosophical terms contrast with] whatever man does or the images of living things he forms [in his mind]. His Name [i.e., God Himself] alone is too exalted to be [described] in terms of substance/essence, let alone accident/attribute. However, because the speaker [of Scripture] is human, and likewise the hearer, the Torah spoke in the language of human beings (dibrah Torah ki-leshon bnei adam) so that the hearer may understand. And similarly, they treated the earth as if it had human form, [as in verses like]: "And the earth opened its mouth" (Numbers 16:32), [and phrases like] "from the recesses/ends (mi-yarketei) of the earth" (e.g., Jeremiah 6:22). [Thus, "laughing" is anthropomorphic language used for human understanding]. And -lamo [in yil'ag lamo - "will mock them" in v. 4]: Is like lahem (לָהֶם - to/for them) [an archaic pronoun form]. And the word la'ag (לַעַג - scorn, derision): Is always [found] with the letter Lamed [as a prefix to the object being scorned], like (Psalm 22:8) "they mock me" (yal'igu li) [and (Psalm 80:7)] "therefore our enemies mock them" (ve-oyveinu yil'agu lamo). [This is] a manner of expression (derekh kinuy - perhaps meaning 'idiomatic usage' or 'reference'), as I will explain [elsewhere, or referring perhaps to the specific usage here].