Question Summary:
When should one perform a minimal wudu? For example, if I walk in the mosque and Isha is taking place and the imam is on the first rakah, do I do a minimal wudu? What if I won’t miss the congregration if I do a full wudu?

Question Detail:

When should one perform a minimal wudu? For example, if I walk in the mosque and Isha is taking place and the imam is on the first rakah, do I do a minimal wudu? What if I won't miss the congregration if I do a full wudu?

Answer :

In the name of Allah, Most Gracious, Most Merciful
Assalaamu `alaykum waRahmatullahi Wabarakatoh
There are two points of discussion regarding the question:-
1)- If there is certainty that the salaah with congregation will be missed , then in this case it will be permissible to perform a minimal wudhu to ensure that salaah with congregation is attained .
لو خاف انّه لو صلى سنة الفجر بوجهها تفوته الجماعة و لو اقتصر فيها بالفاتحة و تسبحة فى الركوع و السجود يدركها فله ان يقتصر عليها لانّ ترك السنة جائز لادراك الجماعة
    Radul Muhtaar Pg 58 Vol  2 [ H M Saeed]
2)- If it is certain that salaah with congregation will not be missed then a further three situations arise:-
            a) If by making a complete wudhu Takbir-Oola is missed but the first rakaah is attained , then in this case a complete wudhu should be performed .
ان ظنّ انّه تفوته التكبيرة الاولى فالتثليث افضل .  و اذا فاتته التبيرة الاولى فقط , لم تفته الصلاة بالجماعة اجماعا , حتى لو كان يدرك الامام راكعا , و يحصل معه الركوع حيث لا تفوته الركعة فاتيانه  يسنّة التثليث افضل من ادراكه اوّل الركعة , لانّ  ادراك التكبيرة مع الامام فضيلة لا سنّة                                
Nihaayatul Muraad Allama an-Naablusee Pg 114 [ Darul Beiruti]
            b) If  one commences wudhu at such a time wherein , if the complete wudhu is performed , the first rakaah of the salaah will be missed , however if a minimal wudhu is performed the first rakaah of salaah will be attained , then in this case it is preferable to perform a minimal wudhu and attain the first rakaah.
 
ان ظنّ انّه ان ثلث الوضوء تفوته ركعة من الصلاة مع الجماعة يترك التثليث
Nihaayatul Muraad Pg 114

            c) If  wudhu is commenced at such a time wherein the first rakaah has already finished and if a complete wudhu is performed there is relative surety that salaah with the congregation will be attained , even if it is the last rakaah , then in this case it would be preferable to perform the complete wudhu.
انّ من ادرك ركعة من الظهر مثلا فقد ادرك فضل الجماعة و احرز ثوابها و كذا لو ادرك التشهد يكون مدركا لفضيلتها على قولهم لانّ المدار هنا على ادراك فضل الجماعة و قد اتّفقو على ادراكه بادراك التشهد فيأتى بالسنّة اتّفاقا
Radul Muhtaar Pg 56 Vol 3 [HM Saeed]
And Allah knows best
Wassalam
Ml. Abdul Hameed,
Student Darul Iftaa
Checked and Approved by:
Mufti Ebrahim Desai
Darul Iftaa, Madrassah In'aamiyyah