“Herein we shall resemble God in His goodness, which is the greatest glory: “Ye shall be the children of the Highest, shall be owned by Him as His children, being like Him.” It is the glory of God that He is kind to the unthankful and to the evil, bestows the gifts of common providence even upon the worst of men, who are every day provoking Him, and rebelling against Him, and using those very gifts to His dishonour. Hence He infers (Luk 6:36), Be merciful, as your Father is merciful; this explains Mat 5:48, “Be perfect, as our Father is perfect. Imitate your Father in those things that are His brightest perfections.” Those that are merciful as God is merciful, even to the evil and the unthankful, are perfect as God is perfect; so He is pleased graciously to accept it, though infinitely falling short. Charity is called the bond of perfectness, Col 3:14. This should strongly engage us to be merciful to our brethren, even such as have been injurious to us, not only that God is so to others, but that He is so to us, though we have been, and are, evil and unthankful; it is of His mercies that we are not consumed.”

— Matthew Henry on Luke 6.36