293. Removing the Knives
44:4 The accepted practice is to remove, or at the very least cover, the knives before bentching. This is because our tables are like the altar, upon which no metal was allowed (Deuteronomy 27:5). The reason for this is that the altar is meant to lengthen our lives, while iron implements (i.e., weapons) shorten lives. Like the altar, our tables can lengthen our lives, through the mitzvah of hospitality. In some places the custom is not to remove the knives on Shabbos and holidays but they should still be removed on weekdays. This is because they are emblematic of Esau’s might but these symbols do not apply on Shabbos.
44:5 Bentching is recited even if one ate only an olive-sized piece of bread. (This is a Rabbinic enactment; one is only required Biblically if he ate until he was sated – Mishnah Brurah 184:22.)