Who among the following was the longest serving chairman of Senate?

Wasim Sajjad is the longest-serving Chairman of the Senate in Pakistan, serving the role for an impressive twelve years. A member of the Pakistan Muslim League (N), Sajjad first took over the role on December 24, 1988, and went on to secure re-election in 1991, 1994, and 1997, serving the role until October 12, 1999. Throughout his tenure, Sajjad also served the role of the President of Pakistan on several occasions.