On a Line of Poetry Attributed to Ferdowsi(You are the beginning and the end of the universe)

One of the famous stories about Ferdowsi is that a Sheikh, who had not prayed on his body, dreamed at night that Ferdowsi was in heaven due to one line of poetry.   In most sources, the line, which led to his salvation, is noted as: You are the beginning and the end of the universe/I do not know what you are but you are everything. Two oldest sources that mention the story and bring the line of verse are Selected History and Zafarnameh (Tarikh-e Gozideh & Zafarnameh) by Hamdallah Mostofi; but it is also mentioned in in texts prior to Mostofi’s works without reference to the story. Mersad al-'Ebad is the first source which mentions the verse without the name of the poet. Qarshi’s Orazat al-Aruzeyn is the oldest document that has attributed it to Shahnameh. This line appears in only three manuscripts of Shahnameh from the 8th and 9th centuries in the story of the fight between Rustam and the emperor of China while it is not mentioned in accredited manuscripts. Hence, in contrast to what has been mentioned from 7th century to the present time, this line does not belong to Ferdowsi.