Matthew 18:16

16 But if they will not listen, take one or two others along, so that ‘every matter may be established by the testimony of two or three witnesses.’a

Read Matthew 18:16 Using Other Translations

But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.
But if he does not listen, take one or two others along with you, that every charge may be established by the evidence of two or three witnesses.
But if you are unsuccessful, take one or two others with you and go back again, so that everything you say may be confirmed by two or three witnesses.