Is the Hadith "Whoever recites 'Qul Huwa Allahu Ahad' (Say: He is Allah, the One) a thousand times on the Day of Arafah will be granted whatever he asks for" authentic, and what is the best supplication on the Day of Arafah?

The aforementioned hadith was narrated by Umm Salamah from Abu al-Sheikh, elevated (marfu‘) with the wording: "Whoever recites 'Qul Huwa Allahu Ahad' (Surat al-Ikhlas) a thousand times on the eve of Arafah, Allah عز وجل will grant him whatever he asks for." We were unable to ascertain its chain of narration (sanad).