What is the scholars' explanation of the Hadith regarding the virtue of the opening takbir (Takbirat al-Ihram) for forty days? Is continuity required for the forty days? And what is meant by "attaining" the opening takbir? Is one considered to have attained it if they catch the Imam before bowing (rukūʿ) after the recitation of Al-Fatiha?

Al-Tirmidhi narrated that the Prophet, peace and blessings be upon him, said: "Whoever prays to Allah for forty days in congregation, catching the first takbir, will be granted two immunities: immunity from Hellfire and immunity from hypocrisy." Al-Mubarakpuri explained the hadith (definition) in Tuhfat al-Ahwadhi, stating that "whoever prays to Allah" means sincerely for Allah for forty days and nights in congregation, and "catches the first takbir" means the takbirat al-ihram (definition) (opening takbir) with the imam, which is the most preferred interpretation. "Immunity from Hellfire" means deliverance and salvation from it, and "immunity from hypocrisy" means that Allah will protect him in this world from the actions of hypocrites and in the hereafter from what hypocrites are punished with. It appears that the forty days must be continuous, based on what Al-Bayhaqi narrated from Anas: "Whoever perseveres in the obligatory prayers for forty nights, not missing a single rak'ah, Allah will grant him two immunities thereby: immunity from Hellfire and immunity from hypocrisy."