Ambrose of Milan

Therefore, we know that above all faith should commend us to God. When we have faith, let us strive for our works to be perfect. For this is a full and perfect sacrifice, as the Lord himself teaches us, saying: 'You shall offer to me your gifts and offerings on my feast days, without detracting or dividing them; but offering them in full, intact, and perfect.' Now, the feast day of the Lord is where the grace of perfected virtues resides. …

On Cain and Abel ↗