What Old Testament text did Jesus use ?

[Tyndale]

Paul wasn't present with Christ in the Gospels either from what I read of it.

Luke says otherwise in Acts

Luke mentions what Paul says to the elders from the church of Ephesus.

Acts 20:35 "I have shewed you all things, how that so labouring ye ought to support the weak, and to remember the words of the Lord Jesus, how he said, It is more blessed to give than to receive."

Paul is quoting Christ, as an eyewitness to his message. Remember, just because Paul was converted after Christ's resurrection, doesn't mean he did'nt hear him preach before the crucifiction.