Following are a number of back-translations of 1 John 2:4:

• Uma: «The person who says: ‘I know [emphatic] God,’ yet he doesn’t follow his commands, he is lying and does not take-to-heart the true teaching.» (Source: Uma Back Translation)
• Yakan: «If there is a person saying that he knows God but he does not follow/obey his commands, that person is a liar and there is no truth in his liver.» (Source: Yakan Back Translation)
• Western Bukidnon Manobo: «However, if there is someone who says, ‘I am now the friend of God,’ but that one who speaks does not obey the commands of God, he is a liar. He does not obey the true doctrine.» (Source: Western Bukidnon Manobo Back Translation)
• Kankanaey: «So if someone says that he knows God while-at-the-same-time he is not following his commands, he is a liar and the true teaching is not in him.» (Source: Kankanaey Back Translation)
• Tagbanwa: «If there is someone who says, ‘I know him all right,’ but he isn’t obeying his commands, he’s only lying. He really has no knowledge at all of the truth.» (Source: Tagbanwa Back Translation)
• Tenango Otomi: «But whoever says, ‘I know God,’ he says, and he does not do what God commands, this is a person who lies, it is not true that he is an acquaintance of God.» (Source: Tenango Otomi Back Translation)
• Yatzachi Zapotec: «If we say that we know him, but we do not do what he commands, we are liars and do not walk with (speak) true words.»
• Eastern Highland Otomi: «One falsely says, ‘I know God,’ and he doesn’t do his Word, then he is lying. And the Word of God hasn’t entered his heart.»
• Tzotzil: «If we say ‘I am a child of God,’ if we do not obey his commands, we are lying. We say it in vain.» (Source for this and two above: John Beekman in Notes on Translation 12, November 1964, p. 1ff.)
• Candoshi-Shapra: «If someone says, ‘I learned (come to a knowledge of) Jesus,’ but throws away (disregards) His orders, he is a liar. He isn’t doing straight at all.»
• Yanesha’: «Whoever says, I, I know how he is, however, if he doesn’t reserve on him his word as he tells us, he is just deceiving. It hasn’t arrived on his heart the words true.»
• Aguaruna: «but he who ‘God is like that saying I know’ says and nevertheless not being an obeyer of His Word, lying he says it. He does not speak truly.» (Source for this and two above: Mildred Larson in Notes on Translation, July 1965, p. 1-15)