Someone wrote to Hazrat Amirul Momineen, Khalifatul Masih Vaa and asked whether a hadith, according to which the first [Muslim] soldier to enter Constantinople would go to Paradise, was authentic. Huzoor-e-Anwaraa, in his letter dated 14 December 2020, gave the following reply to this question:
“Allah the Exalted sent the Holy Prophetsa to the world with the teaching of peace and love. However, when the opponents of Islam went to extremes in their opposition, Allah the Exalted allowed the Muslims to wage jihad in defence (Surah al-Hajj, Ch.22: V.40), whereby the Muslims boldly countered those with the help and support of Allah the Exalted who had attacked them. Moreover, they also conquered areas and countries with the permission of Allah in which conspiracies were being hatched to annihilate the peaceful community of the Muslims and where other tribes and areas were being incited against the Muslims.
Upon being informed by Allah the Exalted, the Holy Prophetsa made numerous prophecies of successful victories of the Muslims in their wars against oppression and barbarism. One of those prophecies was that the Holy Prophetsa said, ‘Those of my ummah who will go out to fight against the City (of the Christian government) of Caesar (from among the two great powers of the time i.e. Caesar and Khosrow) will enter Paradise.’ (Sahih Bukhari, Kitab al-jihadi wa s-siyar)
Similarly, in another place, the Holy Prophetsa said, ‘What a wonderful leader will be the leader of the army that will conquer Constantinople, and what a wonderful army will that army be!’ (Musnad Ahmad ibn Hanbal, Hadith 18189)
The prophecy mentioned in these two ahadith was fulfilled in all its glory in due time like the other divine prophecies given to the Holy Prophetsa by Allah the Exalted.”