Alma is reminding us that we should be imparting our surplus to those in need directly to them, and those who have no extra should not be imparting but receiving. Alma is also saying there is no removal of privileges from the church if we don’t fore we should give of our own free will and desires towards God.
Mosiah (LDS 18:27-29) (RLDS 9:60-64)
27 And again Alma commanded that the people of the church should impart of their substance, every one ACCORDING TO THAT WHICH HE HAD; if he have more abundantly he should impart more abundantly; and of him that had but little, but little should be required; and to HIM THAT HAD NOT SHOULD BE GIVEN.
28 And thus they should impart of their substance of their OWN FREE WILL AND GOOD DESIRES TOWARDS GOD, and to those priests that stood in need, yea, and TO EVERY NEEDY, naked soul.
29 And this he said unto them, having been commanded of God; and they did walk uprightly before God, IMPARTING TO ONE ANOTHER both temporally and spiritually according to their needs and their wants.