Is it sufficient for two men to pray in congregation at home, with one acting as Imam and the other as Ma'mum?

For congregational prayer (Salat al-Jama'ah), two individuals suffice: an Imam and a follower (Ma'mum), whether this is in a home or elsewhere. The proof for this is the hadith narrated by Malik bin Al-Huwayrith, may Allah be pleased with him, that the Prophet, peace and blessings be upon him, said: "(When the time for prayer comes, then give the call to prayer (Adhan) and the call to commence prayer (Iqamah), then let the elder among you lead you in prayer)." This is also indicated by the hadith of Abu Sa'id Al-Khudri that the Messenger of Allah, peace and blessings be upon him, saw a man praying alone and said: "Will not a man donate to this one and pray with him?" Nevertheless, a man must perform congregational prayer in the mosque. It is not permissible for him to pray the obligatory prayer at home, whether in congregation or alone, except for a valid excuse.