In Cracow about 600 years ago, a rare incident took place, which had clear implications on the superiority of our mitzvos, over any other instruction or will.
It happened when the great R’ Yitzchok was the Rov of Cracow, which at the time was owned by a Polish prince. The manager of the prince’s estates was was a Yid named Shlomo Seligman, who was a Kohen, but was far from observant enough to care about his Kehuna. One of the special commandments for a Kohen is that he may not marry a divorcee, but this didn’t matter to Shlomo when he decided that he wanted to marry a divorced woman from Cracow. The woman’s family wanted the marriage to be according to Jewish law and so they had the groom approach the city’s Rov to ask him to officiate at the wedding.
The Rov naturally refused to officiate at the wedding no matter what Shlomo said. Shlomo got some support from relatives and friends, and this gave him the courage to go ahead with his unlawful act.
Shlomo approached his employer, the prince, and told him about the trouble he was having in arranging the wedding. The prince gave his word that he would help make the wedding happen.
He then summoned the Rov, and he asked the Jew-hating bishop to be present as well.
After the Rov explained that the Torah absolutely forbids a Kohen to marry a divorced woman, and therefore he was prohibited from officiating at the wedding, the prince asked the bishop if he agreed to the Rov’s viewpoint on the issue. The bishop then got involved in myriads of irrelevant discussions relating to the ability of rabonim, religion in general, and other topics to try to make a fool out of the Rov, and to belittle him and Yiddishkeit. The Rov being well prepared from knowing generations of these debates easily won the verbal battle against the bishop.
When the prince saw that the bishop had lost, (and the purpose of bringing the bishop to the discussion was wasted), he steered the discussion back to Shlomo’s marriage, and commanded that the Rov, in spite the law of the Torah, should officiate at Shlomo’s wedding.
The Rov calmly replied, “I would gladly carry out your command, but I am first bound by the orders of the A-lmighty who created the heavens and earth, and I will therefore not perform the ceremony for Shlomo.”
Furiously the prince said, “We shall see who will prevail.”
A few days later the Rov was confronted by a band of soldiers, on orders from the prince, and was brought to the marketplace where the wedding ceremony was to take place before a large crowd. Upon arriving at the marketplace, the Rov began to plead with the families that they do teshuva and abandon their foolish ways. He also warned them that whatever happens will be only because of their sin.
All of the Rov’s words were met with ridicule and insults. After several attempts to get them to repent, the old Rov raised his eyes heavenward and called out in a loud voice, “Hashem, these people are trying to make me go against your mitzvos. Please Hashem, send brochos to those who serve you and punish those who sin against you.”
 The Lubavitcher Rebbe’s Memoirs, vol. 2, pg. 214.