A Muslim brother forgot somehow to remember to pray Isha until he was going to Fajr prayer at the Masjid. What should he do to make up for Isha and Witr that he forgot?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions. Al-Bukhari and Muslim reported from Anas (Radiya Allahu Anhu) that the apostle of Allah said: "Whoever sleeps and misses a prayer or forgets to pray it, should pray it as soon as he remembers it and there is no expiation on him for that" . Abu Dawood , Al-Tirmizi and Ibn Majah also reported that the Prophet (Sallallahu Alaihi wa Sallam) said: "Whoever sleeps before praying his Witr, he should pray it when he remembers it" . And in another narration: "When he wakes up in the morning" . Basing on the above, anyone who forgets to pray Isha, he should pray it as soon as he remembers it. The same rule applies to Witr. Allah knows best.