Sayyiduna Ali (may Allah be pleased with him) says concerning the saying of Allah Almighty "al-ma'un" [Surah al-Ma'un: 7]: It means the obligatory zakah. This same view is also reported from Sayyiduna Ibn Umar (may Allah be pleased with them both) and Sayyiduna Anas bin Malik (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7228