Rav Nisim Gaon explains that Yitzchok had been named by Hashem from before birth thus it was always the same.
Now may be a good time for a gem of Torah study.
www.GemsofTorah.com
Sunday, November 13, 2011
Power of Names
Why is Avram's name changed to Avraham & Yaakov receives an additional name Yisroel , but Yitzchok's name remains Yitzchok ?