Ahmad also recorded this narration from Sayyidah Aishah (may Allah be pleased with her); she says: The first prayer that Allah Almighty made obligatory upon the Prophet (peace and blessings be upon him) was two rak'ahs and two, except for the Maghrib prayer, which had three rak'ahs. After that the narrator mentioned the hadith as before. The narrators of all these narrations are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2933