Swearing by the Master of Avrohom
The Raavad's fierce oaths in defence of the Rif drew a dry reply from Rav Zecharya HaLevi.
When the Raavad defended the Rif against the Baal HaMaor, Rav Zecharya HaLevi, he did not hold back. His glosses are full of strong words, and in many places he swears to the truth of what he writes, saying by his own life, by the crown of the King, and by the Master of Avrohom.
Rav Zecharya was not impressed. In his reply on the sugya of HaSho'el in Bova Metzia, quoted by the Shitah Mekubetzes at daf 98b, he answered that even if the Raavad spent the whole day repeating these oaths, they would still not listen to him.
Yet the Raavad did not step back. He returned to his words and made his case stronger, to settle the position of the earlier sages.
Later tradition tried to explain the sharpness. Rav Baruch Ber Leibowitz passed on a saying that the Raavad chose different harsh words to show different degrees of error in those he answered. On this reading the fierce language was a measuring tool for mistakes in Torah, not an attack on the man.
Source: Shitah Mekubetzes, Bova Metzia 98b (quoting Rav Zecharya HaLevi's reply to the Raavad); Hasagos HaRaavad on the Baal HaMaor.
The Raavad explained that his fierce words were aimed at truth in Torah, not at the person. Before your next disagreement, at home or in a learning group, decide in advance what you want to find out. Ask one real question before you answer, and when the other person makes a good point, say so aloud. Afterward, make a point of greeting him or her warmly, so that the argument stays about the matter and the friendship stays whole.