Taher Saifuddin
Syedna Taher Saifuddin bin Syedna Mohammad Burhanuddin (سيدنا طاهر سيف الدين, 4 August 1888 – 12 November 1965) was the 51st Da'i al-Mutlaq of the Dawoodi Bohras, a section within Shia Islam.
He was the son of the 49th Da'i al-Mutlaq Mohammed Burhanuddin, whose family lineage can be traced back to Syedi Fakhruddin Shaheed.
During his reign, Taher Saifuddin RA adapted the modernisation in Western and European ideas, and over the course of it, he established its benefits for the Bohra community.
This sets him an ideal for the mixture of modernisation, education while being rooted in the traditions and the culture of the Fatimi Heritage and his son and successor Syedna Mohammad Burhanuddin and grandson and his successor Syedna Aaliqadr Mufaddal Saifuddin have continued in his path taking giant strides in the benefit of the community. ,
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Mohammad Burhanuddin (49th Dai)
Syedna Mohammed
Burhanuddin bin Syedna Abdul Qadir Najmuddin  born 18 November 1840 in Surat
, India - died 21 February 1906, was 49th Da'i al-Mutlaq of the Dawoodi Bohra sect.
He was the son of the 47th Da'i al-Mutlaq Abdul Qadir Najmuddin, who belongs to the family lineage of Fakhruddin Shaheed.
After the sad demise of the 48th Da'i al-Mutlaq Abdul Husain Husamuddin the helm of the Dawoodi Bohra sect came into his hands.
He led the community out of a period of indebtedness, disorganization and lack of development within the sect.
Being the son of the 47th Da'i al-Mutlaq he had always been closely associated with the members of the Dawoodi Bohra sect.
For the whole part of his childhood and adolesense till the age of 40 years he served his father.
He was educated by his father in all aspects of religion and the world.
He married Aaisaheba Amatulla Aaisaheba and settled in Surat.
After the demise of his father, he served Abdul Husain Husamuddin with the same respect and dedication that he had for his father.
After he became the 49th Da'i al-Mutlaq he devised a time bound plan to bring about a total turnaround in the prospects of the members of the Dawoodi Bohra community.
In the first five years he concentrated on paying off the debts of the community.
In this effort Abdullah Badruddin lent complete support which resulted in all the debts getting paid off in five years.
The next five years he devoted in restructuring the organisational setup and rearranging the work procedures of the community.
The next five years he worked towards development and growth of the members of the community in particular and the sect as a whole.
He remained as the Da'i al-Mutlaq till 1906.
He appointed or did nass upon his nephew Abdullah Badruddin as his successor and died chanting "Ya Ali, Ya Ali" continuously in his last moments.
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Question: Who is the paternal grandfather of Taher Saifuddin?
Answer: Abdul Qadir Najmuddin