Jamieson, Fausset and Brown on Malachi 3:7-12

7-12. Reproof for the non-payment of tithes and offerings, which is the cause of their national calamities, and promise of prosperity on their paying them.

from ... days of your fathers--Ye live as your fathers did when they brought on themselves the Babylonian captivity, and ye wish to follow in their steps. This shows that nothing but God's unchanging long-suffering had prevented their being long ago "consumed" (Mal 3:6).

Return unto me--in penitence.

I will return unto you--in blessings.

Wherein, &c.--(Mal 3:16). The same insensibility to their guilt continues: they speak in the tone of injured innocence, as if God calumniated them.