1؎: The 13th, 14th, and 15th dates of the lunar month are called Ayyam al-Beed (the days of the bright nights), because during these nights, the moon remains visible from the time it rises until morning, illuminating the entire night.
Explanation & Benefits
Hafiz Muhammad Ameen
Urdu marginal note: By "Ayyam al-Beedh" are meant the 13th, 14th, and 15th dates, because on these nights the moon appears full and remains visible throughout the night.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 2347