Genesis 47:31

וישתחו ישראל AND ISRAEL PROSTRATED HIMSELF — The proverb says: Though the lion is king “when the fox has his time, bow to him” (Megillah 16b). על ראש המטה UPON THE BED’S HEAD — He turned towards the Divine Presence (the Shechinah) (Midrash Tanchuma, Vayechi 3). They (the Rabbis) inferred from this that the Shechinah is above the pillow of a sick person (Shabbat 12b). Another interpretation of על ראש המטה He bowed himself in thanks FOR HIM WHO WAS THE CHIEF (ראש) OF HIS CHILDREN — in thanks because his children were heart-whole with God, and none of them was wicked, for even Joseph who was a king and moreover had been a captive amongst heathen peoples yet maintained his righteousness (Sifré ואתחנן 31).

וַיֹּ֗אמֶר הִשָּֽׁבְעָה֙ לִ֔י וַיִּשָּׁבַ֖ע ל֑וֹ וַיִּשְׁתַּ֥חוּ יִשְׂרָאֵ֖ל עַל־רֹ֥אשׁ הַמִּטָּֽה׃ {פ}

And he said, I will do as thou hast said. And he said, Swear to me. And he swore to him. And Yisra᾽el bowed himself upon the bed’s head.