Lest you might lay him under a curse

Today I learned some words of wisdom from the Mauritania 6th year English textbook: 

"In the north, for example, you'd better not strike anyone with a rosary because that may cause him/her to be sterile and barren!"

"In the center, you are not advised to tread on dirt and soil for demons might be there, and therefore they may go off with you!"

"In the North West, never call out somebody's name while he's leaving his house lest you might lay him under a curse."

"In the West, avoid the word "black", especially when you're traveling because you might undergo horrible accidents or much suffering when you mention that word."