Question Summary:
Status of Hadith on Catching the Imam in Ruku

Question Detail:

 
IS it possible to know status of following two Ahadees, Sahee or not, please aslo share source from where it can verified, like internet link, webiste address: 
1. It was narrated in a saheeh report that Ibn Mas’ood (may Allaah be pleased with him) said: “Whoever does not catch up with the imam when he is bowing has not caught up with that rak’ah.” Narrated by al-Bayhaqi. 
2. Ibn ‘Umar said: “Whoever catches up with the imam when he is bowing and bows before the imam raises his head, has caught up with that rak’ah.” Narrated by al-Bayhaqi. 

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The Ahadith in reference are hereunder:
عن عبد الله يعني ابن مسعود قال: " من لم يدرك الإمام راكعا لم يدرك تلك الركعة " (السنن الكبرى للبهيقي، باب إدراك الإمام في الركوع) 
Narrated by ‘Abullah bin Mas‘ood, he said, “Whoever does not catch the Imam in Rukū‘ has not caught the Rak‘ah”
عن نافع، عن ابن عمر أنه كان يقول: " من أدرك الإمام راكعا، فركع قبل أن يرفع الإمام رأسه، فقد أدرك تلك الركعة " (السنن الكبرى للبيهقي، باب إدراك الإمام في الركوع)
Narrated by Nafi’ from Ibn ‘Umar that he (Ibn ‘Umar) use to say, “Whoever catches the Imam in Ruku’ before the Imam raises his head, he has indeed caught that Rak‘ah.”
The purport of the two Ahādīth in reference is Sahīh. These two Ahādīth and similar ones are mentioned in many major Hadith collections: Abu Dawood, Muwatta’ Malik, Sahih Ibn Khuzaimah, Al Mu‘jam Al Kabir li Al Tabrani, Al Mu‘jam Al Awsad li Al Tabrani, Musannaf ‘Abd Al Razzaq, Musannaf Ibn Abi Shaibah, Sunan Al Daraqutni, etc.
And Allah Ta’āla Knows Best
Hisham Dawood
Student Darul Iftaa
Chicago, USA
Checked and Approved by,
Mufti Ebrahim Desai.