Is it true that the saying, "Hud and its sisters have made me old," refers to one verse in Surat Hud and not to all the verses of the Surahs?

It is authentically reported from the Prophet, peace and blessings be upon him, that he said: "Hud and its sister surahs have made me gray." Its sister surahs are "Al-Waqi'ah (The Inevitable Event), Al-Mursalat (The Emissaries), 'Amma Yatasa'alun (About what do they ask?), and Idha Ash-Shamsu Kuwwirat (When the Sun is wrapped up)." The reason for this is what is mentioned in these surahs concerning the news of the Hour and its horrors, and the punishment that befell the past nations who disbelieved the messengers. It was also said that what made him gray was Allah's saying in Surat Hud: "So remain steadfast as you have been commanded." Al-Qurtubi mentioned, on the authority of Ibn Abbas, that this verse was the most difficult and arduous verse revealed to the Prophet, peace and blessings be upon him. There is no impediment to all of these factors being the cause of his graying hair.