Joining the congregation whilst they are in Sujood
Question: If a person (intending to perform the congregational prayer) finds the imaam in sujood, should he wait until he arises (from the sujood) or should he (immediately) join him (in sujood)?
Response: It is preferable for him to join the imaam in whatever position he finds him in and not to wait; this is based upon the generality of his (sal-Allaahu ‘alayhe wa sallam) statement:
((And whatever you are able to catch (of the prayer) then pray…)), [Transmitted by al-Bukhaaree – 635 and Muslim – 603]
Shaykh Ibn `Uthaymeen
I`laam al-Mu`aasireen bi-Fataawa Ibn `Uthaymeen – Page 55 source:fatwaonline.com