Acts 24:16-20
Acts 24:16 (KJB)
And herein do I exercise myself, to have always a conscience void of offence toward God, and toward men.
Exercise - To endeavor
Paul then states that in his life he had always endeavored to have a clear conscience toward God and toward all men. Paul never behaved in a fashion which would have offended anyone because his lifestyle has proven that he was a very simple man and avoided any hostilities, but unfortunately they always found him. He desired to do good toward all the factions in Judaism but as seen in this event in Jerusalem that there were very different factions in Judaism concerning such beliefs as the resurrection or angels. Paul never looked for trouble nor did he ever use his office of apostle for personal gain.
Acts 24:17 (KJB)
Now after many years I came to bring alms to my nation, and offerings.
Paul had returned to Jerusalem after many years and especially to bring the gift from the other churches to the Jerusalem church. He also wanted to bring an offering unto God. Charitable gifts and offerings are two things which do show that there was no spirit of enmity in Paul but a spirit of caring for his own people.
Acts 24:18 (KJB)
Whereupon certain Jews from Asia found me purified in the temple, neither with multitude, nor with tumult.
Paul showed why his conscience was clear concerning himself. When Paul was presenting his offerings in the temple, he was there as one being purified, thus fulfilling the requirements of the law. The troublemaking Jews from Asia had found Paul in the temple who was being quietly submissive to the fulfilling of the law. He was in the temple without a crowd and without a tumult. He was not in there to stir up any crowd but to be a worshipper. He gave his entire attention to the worship of God. The Jews from Asia had jumped to a conclusion that because they saw Paul with a Gentile, they immediately thought that he brought him into the temple thus defiling it, which was a totally false accusation.
Acts 24:19 (KJB)
Who ought to have been here before thee, and object, if they had ought against me.
Paul then states that since the Jews from the province of Asia were the real accusers, then it should have been they, and not the Jerusalem company who should have made the accusations. These others that came up with the high priest would not have qualified under the law as witnesses because they were only acting on hearsay. The law required that at least two or three real witnesses to an actual event was required but since their accusations were false, they would not be able to prove something which did not happen without lies and false testimony.
Acts 24:20 (KJB)
Or else let these same here say, if they have found any evil doing in me, while I stood before the council,
Paul then basically states that the ones who came from Jerusalem would be unable to make or confirm any real accusations against Paul. Simply because they were not witnesses of anything. It also meant that Paul was accusing them of being disobedient to their own law. Roman law also required the need for witnesses but the most they could produce against Paul was a clever lawyer who had lacked the facts in all areas.