Did Umar ibn al-Khattab, may Allah be pleased with him, receive Ayat al-Kursi from Satan?

The story you mentioned about Ayatul Kursi, attributed to Omar (may Allah be pleased with him), was narrated by Al-Tabarani in his Al-Mu'jam Al-Kabeer from Abdullah ibn Mas'ud. It tells of a Companion who wrestled with a jinn and defeated it three times. On the third occasion, the jinn taught him that reciting Ayatul Kursi in a house expels Shaytan from it. Ibn Mas'ud frowned when asked about the Companion, then said it was Omar (may Allah be pleased with him). This story is not attributed to Shaytan but to a jinn, and Omar already knew the verse before that; the jinn merely taught him its effect in expelling devils.