The Admor Rav Avraham Yeshoshua Heshel of Kopichnitz, z''tl was one of the Gedolim of the past century. He was close with Rav Moshe Feinstein, z''tl, who lived in his neighborhood - the lower East Side. He also became close with Rav Yosef Shlomo Kahanaman when Rav Yosef once traveled to America to raise funds for his Torah institutions in Eretz Yisrael. This friendship eventually resulted in Rav Kahanaman matching up Rav Avraham Yehoshua Heshel's granddaughter with the son of Rav Shlomo Zalman Auerbach z''tl.
When the Admor of Kopichnitz arrived in Eretz Yisrael to attend the wedding, he met Rav Shlomo Zalman for the first time, and developed a warm connection with him. After the wedding, when he was ready to return to America, the Admor went to Rav Shlomo Zalman to bid him farewell. When they heard a honk from outside, Rav Shlomo Zalman accompanied the Admor to the car. However, it turned out that it wasn't the car which was taking the Admor to the airport.
Meanwhile, Rav Shlomo Zalman sent someone to bring a chair for the Admor, and urged him to sit. However, the Admor refused to sit down. The Admor explained, "When I was young, I once heard a wonderful yesod from my father, my teacher, the Admor Rav Yitzchak Meir of Kopichnitz: “Before you take any action, imagine that a photographer is standing opposite of you, and photographing your every move. Take out the pictures and examine them. If you are satisfied with your appearance, you can carry out what you intended. If not, refrain!" "I carried out this cheshbon, and said to myself. “How will I be able to look at a picture of myself sitting, with Rav Shlomo Zalman standing next to me!?"
[Source: Chayim Sheyash Bahem. Special thanks to Revach L’Neshama for the story]
