Jamieson, Fausset and Brown on Song of Solomon 8:12

12. "mine" by grant of the true Solomon. Not merely "let out to keepers," as in the Jewish dispensation of works, but "mine" by grace. This is "before me," that is, in my power [Maurer]. But though no longer under constraint of "keeping" the law as a mere letter and covenant of works, love to Jesus Christ will constrain her the more freely to render all to Solomon (Ro 8:2-4; 1Co 6:20; Ga 5:13; 1Pe 2:16), after having paid what justice and His will require should be paid to others (1Co 7:29-31; 9:14). "Before me" may also mean "I will never lose sight of it" (contrast So 1:6) [Moody Stuart]. She will not keep it for herself, though so freely given to her, but for His use and glory (Lu 19:13; Ro 6:15; 14:7-9; 1Co 12:7). Or the "two hundred" may mean a double tithe (two-tenths of the whole paid back by Jesus Christ) as the reward of grace for our surrender of all (the thousand) to Him (Ga 6:7; He 6:10); then she and "those that keep" are the same [Adelaide Newton]. But Jesus Christ pays back not merely two tithes, but His all for our all (1Co 3:21-23).