I can't say for sure, but I found the quote with some more sentences and a date.
Africa has accepted the challenge of the modern world and with it come grave responsibilities. Many discouraging hours will arise before the
rainbow of accomplished goals will appear on the horizon. African civilization in its potential magnitude must be able to command fortitude,
patience, tolerance, and diligence. To sustain us in all our tasks we count on the women of Africa. Without their relentless vigilance no aspect of our responsibilities can be attained. Women role has never been so demanding, and you can be proud to answer the call for the betterment and future of mankind
- His Imperial Majesty Emperor Haile Selassie I
Dec. 14, 1960