Yerushalmi Kituvot 2: The ramah says that judges sit on erev shabat because of Bitul Hamilamdim. The Gra says the source is Sanhedrin 24. Can't find it.
Thank you for having notes on the Yerushalmi.
Aryeh Shore, Rechovot, Israel
The source of the Rama is the Terumas ha'Deshen 327. There he explains that relatives are normally Pasul to be judges, but if both sides agree to accept them they are permitted to judge. The source is the Mishnah on Sanhedrin 24a Ne'eman Alai Aba. So too if both sides agree, it is permitted to judge on Erev Shabbos. Normally, Erev Shabbos is not allowed because the judges feel pressed for time and can't judge well but if both sides agree it's permitted. Here then is what the Gra meant by Sanhedrin 24.
This was explained by Hagaos of R. M. Y. Ginzberg. The Gra is not bringing the source for Bitul Talmidim. He is bringing the source why it is not forbidden to judge on Erev Shabbos if a good reason such as Bitul Talmidim is given.
All the best,