“Forty-nine alone escapes the Eastern suspicion of anything to do with the number 4 (which has a tonal connection with the Chinese word for death). This is because it is the sum of seven times seven, and ‘seven’ is very propitious because it sounds like ‘arise’ and can also mean ‘togetherness.’ For the superstitious, rather than writing forty-nine by itself, seven times seven is often used or tacked on beside it. So forty-nine has become the Eastern world’s preferred length of time for fasting, and cleansing rituals, as well as being the period of time for a requiem ritual after a death.”
Rogerson, Barnaby. Rogerson’s Book of Numbers: The Culture of Numbers–from 1,001 Nights to the Seven Wonders of the World. New York: Picador, 2013.