Lifting up his eyes to heaven, Jesus prayed saying: "I pray not only for these, but also for those who will believe in me through their word, so that they may all be one, as you, Father, are in me and I in you, that they also may be in us, that the world may believe that you sent me.” (Jn 17:20-26)
https://bible.usccb.org/bible/lecturas/052523.cfm
The High Priestly Prayer of Jesus comes to a conclusion with this passionate plea for unity. In fact, unity among believers is essential so that the “world may believe that you sent me.” Christian Unity can never become pasé. Christian Unity is the constant prayer of Jesus.