By Rabbi David Shasho:
וַיֹּ֥אמֶר פַּרְעֹ֖ה אֶל־עֲבָדָ֑יו הֲנִמְצָ֣א כָזֶ֔ה אִ֕ישׁ אֲשֶׁ֛ר ר֥וּחַ אֱלֹהִ֖ים בּֽוֹ
“And Pharaoh said to his servants, ‘Could we find another like him(Yosef), a man in whom is the spirit of God?’”
The last letters of the words אֲשֶׁ֛ר ר֥וּחַ אֱלֹהִ֖ים בּֽוֹ spell out “חַמוֹר”. The Reishit Chochmah points out that someone who makes himself like a donkey will be able to have the spirit of Hashem come upon him. Someone who can accept the yolk of the Torah by carrying it with him all the time and humbling himself like a donkey will reach great heights spiritually. We find this character trait by Yosef who when tested with very difficult situations always kept his mind focused on his load, the Torah which he carried with him always.
We also find when Yissachar was blessed by Yaakov, he was compared to a donkey. Rashi points out that Yissachar bears the yolk of the Torah like a donkey that carries a heavy load. The donkey travels day and night and has no permanent stable of his own.
Let us learn the lessons of the donkey: to keep the yolk of the Torah with us day and night, to always be humble, and to know that this world is only temporary with no permanence.