What is meant by "catching up with the opening takbir" in the hadith "Whoever prays forty days in congregation" in the following situations: hearing it from outside the mosque, or inside it before reaching the rows, or while performing the pre-prayer supererogatory prayer, or when delaying the prayer for a lesson, or in a mosque that establishes the prayer with unusual speed, or when traveling, shortening, and combining prayers?

The cases mentioned are not considered by jurists as having caught the opening takbir (takbirat al-ihram) because it is caught by the follower witnessing the Imam's declaration of sacredness (tahrim), or, according to another opinion, by catching a part of the standing, or, according to yet another opinion, by catching the beginning of the bowing (ruku'). If the people of the mosque are performing the prayer with its pillars and obligations, one should not absent oneself from them unless there is another congregation. One should be keen to pray in the mosque with the largest congregation.