"And afterward his brother came out, and his hand grasping Esau's heel" (Genesis 25:26). A certain prefect asked Rabban Gamliel, saying to him: who will seize the kingdom after us? He brought a blank sheet of paper, took a pen, and wrote upon it, "And afterward his brother came out, and his hand grasping Esau's heel" (Genesis 25:26). They said: see, old words from the mouth of a new elder [an ancient truth freshly spoken]. This teaches you how much pain that righteous one [Jacob] was pained.
Jacob's Hand on the Heel and Rome's Anxious Question About Succession
Yalkut Shimoni on Torah 110:26
(בראשית כה כו) וְאַחֲרֵי כֵן יָצָא אָחִיו וְיָדוֹ אֹחֶזֶת בַּעֲקֵב עֵשָׂו, הֶגְמוֹן אֶחָד שָׁאַל אֶת רַבָּן גַּמְלִיאֵל אָמַר לֵיה מִי תּוֹפֵס מַלְכוּת אַחֲרֵינוּ, הֵבִיא נְיָר חָלָק נָטַל קֻלְמוֹס וְכָתַב עָלָיו וְאַחֲרֵי כֵן יָצָא אָחִיו וְיָדוֹ אוֹחֶזֶת בַּעֲקֵב עֵשָׂו אָמְרוּ רְאוּ דְּבָרִים יְשָׁנִים מִפִּי זָקֵן חָדָשׁ לְהוֹדִיעֲךָ כַּמָּה צַעַר הָיָה אוֹתוֹ צַדִּיק מִצְטַעֵר.