Additional Sessions Judge A N Naik pronounced the sentence.
Jignesh Patel, a resident of Navagam Karavel in Ankleshwar taluka, was killed at his house about a year ago.
Prime accused Jagdish Patel had an affair with Jignesh's wife, and when it was exposed, he and others attacked the family, according to the prosecution.
One of the accused, Raman Patel, was acquitted by the court. But,Jagdish Patel, Manhar Patel, Deepak Patel, Pankaj Patel, Sandeep Patel, Ishwar Patel, Ankit Patel, Kiran Patel and Vinod Patel were convicted.