Deuteronomy 4:2 gives the same command not to add to God's word, directly paralleling the warning here.

Deuteronomy 12:32 repeats the command not to add or take away from God's word, echoing the warning here.

Revelation 22:18 echoes this same warning: do not add to God's words, or face divine judgment. A clear parallel.

Revelation 22:19 parallels the warning against taking away from God's words, complementing the ban on adding.

Ecclesiastes 3:14 states nothing can be added or taken from God's work, directly paralleling the command not to add to His words.

Galatians 1:9 warns against preaching a different gospel, which is equivalent to adding to God's words, with a curse attached.