When does the praying person catch up with a rak'ah, by the takbir of ruku' or by reciting al-Fatihah?

The questioner : May Allah preserve you, O Shaykh. When does the praying person catch up with a rak'ah, by the takbir or by reciting al-Fatihah?

The Shaykh : By the takbir, not by reciting al-Fatihah. Do you mean the takbir of ruku'?

The questioner : Yes

The Shaykh : There was an old disagreement in this issue among some of the later scholars and others. The four Imams agreed that whoever catches up with the bowing (ruku') with the imam has caught up with the rak'ah. Others among the opponents in this issue, from the majority (jumhur), held that one who catches up with the bowing does not catch up with the rak'ah unless he recites the Opening of the Book (al-Fatihah), based on the hadith narrated by the six Imams from 'Ubadah ibn al-Samit (may Allah be pleased with him), who said: The Messenger of Allah (peace and blessings be upon him) said: This is the one who caught up with the imam while he was bowing; he did not recite the Opening of the Book. So, according to this opponent to the majority's position, he did not catch up with the rak'ah. However, the correct view in this issue is what the majority held, due to some authentic hadiths and athar from some of the great Companions. A hadith came in Sunan Abu Dawud, but its chain is weak and soft; it is from the hadith of Abu Hurayrah that the Prophet (peace and blessings be upon him) said: As we said, regarding Abu Dawud's narration of this hadith, its chain is weak and cannot be relied upon alone. However, the hadith came through another route in al-Bayhaqi's Sunan al-Kubra. Then I found it through another authentic route in some of the manuscripts available in the Zahiriyah Library. I have spoken about this hadith specifically in some of my printed works. This hadith was further supported by some authentic athar in Ibn Abi Shaybah's Musannaf, al-Bayhaqi's Sunan al-Kubra, and others, from Abu Bakr al-Siddiq, 'Abdullah ibn Mas'ud, Zayd ibn Thabit, and 'Abdullah ibn 'Umar "that they used to say that whoever catches up with the bowing has caught up with the rak'ah". These pieces of evidence make the position of the majority of scholars, including the four Imams, stronger in my view, over what al-Bukhari held and some of the Imams of hadith and Sunnah followed him, such as Imam al-Shawkani. So the truth is what should be followed. And we ask Allah, Mighty and Majestic, to show us the truth as truth and grant us the ability to follow it.