Amitabh Bachchan, who's synonymous with his booming baritone, has sung in many of his films over four decades. Once again, he will lend his voice to a soulful song for his upcoming psychological thriller, TE3N. The song titled Kyun Re, which has been penned by Amitabh Bhattacharya and composed by Clinton Cerejo, is pivotal to the movie. The film directed by Ribhu Dasgupta also stars Nawazuddin Siddiqui and Vidya Balan (in a guest appearance crucial to the plot).