The following is an excerpt from Johannes Brenz’ commentary on St. John.
JUST AS THE FATHER LOVES ME [Jn 15:9]
In what way does the Father love the son? He loves Him thus: that He would give to Him all good things, and that He would sustain Him under cross, restore Him from death to life, and free Him from hell. Thus the Son also loves, believing that He receives all the good things that are given from the Father, that He is sustained under cross, restored from death to life, and freed from hell.
IF YOU KEEP MY COMMANDMENTS [Jn 15:10]
You say, “How ought we remain in Christ’s love?” Answer: “If you keep my commandments, you will remain in My love.” Christ says this not so you would understand commandments by the Law of Moses, but that we may believe the Gospel and the Word of Christ, who was sent from the Father, and love our enemies, just as Christ loved us. For the following are the commandments from the Father that were demanded of Christ, His Son. First, that He would descend from heaven and clothe Himself with flesh. Then, that He would love us and die for our salvation.
From this it is added, “Just as even I have kept the commandments of My Father and remain in His love.” That is, “I descended from heaven, took up the from of servant, and have become obedient to the Father even to the death of the cross. So even you yourselves are obedient to Me through faith and love your enemies, diminishing yourselves below the lowest of the low. Psalm [40:7–8]: “Then I said, behold, I come. In the chapter of the book it is written concerning me: I delight to do Your will, O my God, and Your Law is within My heart.”