A man from the tribe of Juhaynah narrates: I asked the Prophet (peace and blessings be upon him): When should I offer the Isha prayer? The Prophet (peace and blessings be upon him) said: When the night fills the bottom of every valley.
Imam Ahmad recorded it, and its narrators have been declared trustworthy.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 1753