It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that he explained these four drinks and added: "And khamr is from grapes, and sakar is from dates." Abu Ubayd said: Among them is al-sukrukah, and its explanation has been narrated from al-Ash'ari, who said: It is made from corn.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأشربة والحد فيها / 17386