“He who has My commandments and keeps them is the one who loves Me; and he who loves Me will be loved by My Father, and I will love him and will disclose Myself to him” (John 14:21, NASB).
Jesus promised to “disclose” Himself (or “reveal” or “manifest” Himself, as other Bible versions translate it) only to certain people, namely, those who keep His commandments. Why? The revelation of Himself is a reward for loving Him, something which is manifested by keeping His commandments. Very simple.