What is the meaning of the Prophet's (peace be upon him) saying to Umar ibn al-Khattab (may Allah be pleased with him): "You have spoken truthfully... for nothing is ever completed but it then نقص [diminishes or becomes imperfect]," after the revelation of the verse "This day I have perfected for you your religion," and Umar's weeping?

The meaning of Umar's saying (may Allah be pleased with him): "Nothing was perfected but it declined" is clarified by the hadith: "Indeed, Islam began as something strange, and it will return as something strange, so blessed are the strangers." His saying: "and it will return as something strange" agrees with the meaning of Umar's statement. Islam began in a state of scarcity and weakness, then it spread and became strong, and it will return weak and strange as it began.