Is the prayer deemed caught (idrak) if one joins the congregation after performing less than one full rak'ah?
Chapter on Prayer Times
Al-Mughni
Book of Prayer
Primary text
The prayer is not deemed caught unless one joins for at least one full rak'ah. This is the apparent position in the statements of Al-Khiraqi and the Madhhab of Malik. The evidence cited is the apparent meaning of the narration stating that catching one rak'ah indicates that less than that does not suffice for catching the prayer. Furthermore, since it is an attainment of the prayer, it cannot be attained with less than a full rak'ah, similar to catching the Friday prayer (Jumu'ah).
Supporting text
A second view holds that the prayer is deemed caught upon attaining any part of it, no matter how small. Al-Qadi stated that the apparent meaning of Ahmad's words is that one has attained it upon perceiving any portion of it. Abu Al-Khattab stated that whoever catches the amount of time required for the initial Takbir (Takbirat al-Ihram) before the time for prayer expires has attained it. This is the position of Abu Hanifah. Al-Shafi'i has two opinions corresponding to these two views.