Verses with the word muzzle in the New Testament (2 verses):

1 Corinthians 9:9
For it is written in the law of Moses, Thou shalt not muzzle the mouth of the ox that treadeth out the corn. Doth God take care for oxen?

1 Timothy 5:18
For the scripture saith, Thou shalt not muzzle the ox that treadeth out the corn. And, The labourer is worthy of his reward.