I read somewhere that Adi SankarAcharya cursed Keralite Hindus. Basically, the post claimed that dwindling numbers of Hindus in Kerala is due to Adi Sankara's curse to Kerala that the people there will be devoid of Vedas. I doubt that claim since Adi Sankara was Himself from Kerala and He debated for superiority of Vedas and Advaita. But still I want to know if Adi Sankara really cursed anyone.
As per Sringeri official site, Abridged Madhaviya Shankara Digvijayam, part-4, Shankaracharya visits her mother when she is sick, and then he gives her knowledge of supreme brahman, after listening that she dies. Since he is sanyasin and has rejected fire and rituals related to that, he requests relatives and neighbours to help, to that they don't come for help. That's why Shankaracharya curse them to be incompetent of Vedas.
Shankara’s boon to Aryamba During this time the Acharya had an intuition that his mother was passing through her last days and informed his disciples. The great Siddha that Sri Shankara was, he transported himself to Kaladi in no time. On seeing the worn out condition of his mother he prostrated before her. Aryamba was freed from all distress on seeing him. In spite of his being a Sanyasin, known for non-attachment, he became tender in his heart on seeing his mother. On Aryamba’s request about the knowledge of the Supreme, Sri Shankara began to instruct her on the Impersonal Brahman which however she could not absorb. Then he recited a hymn on Shiva, which brought in the emissaries of Shiva with tridents and the rest. The mother appeared frightened. Then he recited a hymn on Vishnu on hearing which she saw the radiant form of Pure Consciousness within. Aryamba left her mortal coil with her mind absorbed in the Lord. When the Acharya called his neighbours and former relatives for help in cremation, they scorned at him thus, ‘O Sanyasin, what rights do you have to perform such rites?’ They stood adamant and refused even to give fire to cremate the body. Unperturbed by their stand, the Acharya himself generated fire out of his own right hand and completed the cremation. Then he cursed the people of the place, ‘May you become incompetent to study the Vedas! May no Sanyasin visit your place for bhiksha! May you cremate your dead bodies in your own house compounds!’