William Burkitt on Matthew 16:22

No doubt Peter spake all this out of a sincere intention, and with a singular affection towards our Saviour; but pious intentions and good affections will not justify unwarrantable actions.

From this counsel of St. Peter to Christ we learn,

1. How ready flesh and blood is to oppose all that tends to suffering; Master, spare thyself.

2. What need we have to be fortified against the temptations of friends as well as of enemies! for Satan can make good men his instruments to do his work, when they little think of it,. Peter little suspected that Satan set him on work to hinder the redemption of mankind, by dissuading Christ from dying. But observe in the next verse with what indignation Christ rejects Peter's advice.