פירוש על ברכות 106:32

AND YOU SHALL BE HOLY, THESE ARE THE FINAL WATERS. It seems from Tosfos that it was not the common custom to wash one’s hand at the end of the meal. From the Gemara it is quite clear that it is required and as long as one does not wash his hands he may not recite birchas hamozon. Tosfos wishes to reconcile the custom of his time with the Gemara. It is exclusively for the times of the Gemara that they regularly washed their hands after the meal because of the possibility that some of the salt may have come from S’dom and it would be harmful if one would not wash his hands after the meal. However, we who do not have S’dom salt available in our hands and we therefore we do not regularly wash our hands after the meal, the lack of washing does not prevent us from reciting birchas hamozon.
However, fastidious people who regularly wash their hands after the meal, for them, not washing one’s hands definitely prevents them from reciting birchas hamozon and they must wash their hands before birchas hamozon.

Lit. "the first water" — "the latter water."

The Hebrew text omits "the Lord your God." There is some confusion between Lev. xi. 44 and ibid. xx. 7.