the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
The Permanent Fatwâ Committee of Saudi Arabia issued a fatwâ on this topic. They declared that since a person who commits suicide is still a Muslim, he must have a funeral prayer performed for him.
It is a major tenet in the creed of Ahl al-Sunnah wal Jamâ`ah that Muslims who commit major sins remain Muslims and do not become disbelievers by committing such sins.
However, it is permissible for the leader of the Muslim community to abstain from performing the funeral prayer in such circumstances and let others do it. This is similar to what our Prophet (peace be upon him) used to do by abstaining from offering the funeral prayers for those who engaged in major sins.
Source: Islam Today