# who said about his father and mother

The word "who" refers to the Yahweh's "faithful one" of  Deuteronomy 33:8. This is the tribe of Levi.

# your word

"your commands"

# guarded ... kept

These words often refer to "obeyed," but here they should be translated literally because they refer to a time when the Levites literally killed people who were rebelling against Yahweh.