The first revelation
Islamic tradition remembers her as the first person to believe in Muhammad’s ﷺ message. Accounts of the first revelation emphasize her reassurance and her recognition of his concern for relatives, guests, and people in need.
Source: TDV Encyclopaedia of Islam — Khadija bint Khuwaylid
Years of support
Khadija supported Muhammad ﷺ and the early believers through social pressure and hardship. She died before the Hijrah. Her remembered importance rests on this sustained support, rather than on a securely agreed age at marriage or birth date.
Source: TDV Encyclopaedia of Islam — Khadija bint Khuwaylid