What is the minimum number required for congregational prayer (Jama'ah)?

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Congregational prayer is established with two people or more. There is no known disagreement on this ruling. Evidence for this is the Hadith narrated by Abu Musa, where the Prophet peace be upon him stated: "Two and anything above them is a congregation," recorded by Ibn Majah. Furthermore, the Prophet peace be upon him instructed Malik ibn al-Huwayrith and his companion: "When the time for prayer comes, let one of you give the call to prayer, and let the eldest of you lead you in prayer."