For the administration of this service - The distribution of this proof of your liberality. The word “service” here, says Doddridge, intimates that this was to be regarded not merely as an act of humanity, but religion.
The want of the saints - Of the poor Christians in Judea on whose behalf it was contributed.
But is abundant also by many thanksgivings unto God - Will abound unto God in producing thanksgivings. The result will be that it will produce abundant thanksgiving in their hearts to God.