Imam Husayin (as) said: The Light in the verse, "They desire to extinguish God’s Light with their mouths" refers to Hz. Mahdi (as).

They desire to extinguish God’s Light with their mouths. But God refuses to do other than perfect His Light, even though the irreligious detest it. (Surat at-Tawba, 32)

Muhammed bin’il Fudayl explains Imam Husayin’s (as) interpretation as follows:

“THE ‘LIGHT’ RELATED IN THIS VERSE IS THE IMAMATE. GOD WILL MAKE THE IMAMATE COMPLETE WITH MAHDI (AS) .”

Springs of Mawaddat, Suleyman Ibrahim, page 234