בראשית פרק מו, א ֹלאֵל םיִּחָּבְּז חַ בְּזִּ
יַו עַבָּ ש הָּרֵאְּ ב אֹבָּ
יַוקי אָּבִּיו יִּצְּחָּק
(הגהות רמ"א ליו"ד ס' ר"מ סכ"ד) לאלקי אביו אברהם לא נאמר, אמר רבי יוחנן, מלמד שחייב אדם יותר בכבוד אביו יותר מכבוד אבי אביו (מ"ר), לפי דרכנו למדנו, שחייב אדם גם בכבוד אבי אביו, אלא שכבוד אביו חייב יותר
The Mahari from Kolin disagrees and holds that one is not obligated to honor one’s grandfather at all. Many Achronim discuss this subject. The Gra writes a new idea that a person is certainly not obligated to honor one’s maternal grandfather (one’s mother’s father). He mentions that in the Gemara that the sons of daughters are not considered like grandsons. However, Rabbi Epstein brings many places in the Gemara where the sons of daughters are considered like grandchildren. Therefore, he declares that the Gemara agrees with the Rema, and the words of the Gra need to be reviewed.
According to the opinion that one is obligated to honor one’s grandfather, then the reason that one should honor one’s grandfather more than one’s father, since one’s father is also obligated to honor his father. We see such an opinion in the Rishonim. In the law of reciting a blessing at the site where a miracle occurred to one, then one’s children and grandchildren should also recite a blessing if they come to that place. The loving feeling of the grandfather extends to the grandchildren and is returned from the grandchildren to the grandfather. Thus, the grandchildren recite a blessing with G-d’s name and reference to his Kingship, as the obligation extends to the grandchildren to honor their grandfather.
