https://masjidfurqan.co.uk/2018/05/21/when-the-prophet-asked-ubay-which-aayah-in-the-quraan-is-the-greatest-the-response-he-gave-shows-us-the-lofty-station-of-tawheed-in-the-hearts-of-the-sahaabah-by-shaikh-abdur-razzaaq-a/