It is narrated from Sayyiduna Bishr Khath'ami (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Constantinople will certainly be conquered; its commander will be the best commander and that army will be the best army." He says: Maslamah bin Abdul Malik summoned me and asked me about this, so I narrated this hadith to him, thus he attacked Constantinople.