Gesenius' Hebrew Grammar/160. Concessive Clauses
a Besides the use of the imperative in the sense of a concession, meant either seriously (§ 110 a) or mockingly (§ 110 f), and of concessive circumstantial clauses (§ 141 e, § 142 d, and § 156 f), concessive clauses may be introduced—
(a) By a simple אִם if: thus Jb 9 with perfect, if (=though) I had been in the right; Is 1 and 10:22 with imperfect in reference to a contingent event.
b (b) By גַּם כִּי yea though, Is 1 with imperfect; for which we find simply גַּם in Is 49 with imperfect, yea, though these may forget, yet ...; on the other hand, with perfect, Jer 36, ψ 95, Neh 6; finally כִּי גַם even if, though, Ec 4. c (c) By the preposition עַל־ governing a complete noun-clause, as Jb 16 עַל לֹֽא־חָמָס בְּכַפָּ֑י notwithstanding that no violence is in mine hands, or a verbal-clause, Is 53. On עַל־ with the infinitive in a similar sense (equivalent to in addition to the fact that = notwithstanding that), cf. § 119 aa, note 2.