We know that we have come to know him if we keep his commands. (NIV)
And this is how we may discern [daily, by experience] that we are coming to know Him [to perceive, recognize, understand, and become better acquainted with Him]: if we keep (bear in mind, observe, practice) His teachings (precepts, commandments). (AMP)
And hereby we do know that we know him, if we keep his commandments. (KJV)