Is a girl considered his sister through rada'a (wet-nursing) if she was nursed by his mother while he was not yet forty days old?

Scholars have differed regarding the amount of suckling that causes prohibition (of marriage). The relied-upon view is that prohibition does not occur with fewer than five sucklings, based on what Aisha (may Allah be pleased with her) narrated: "Ten known sucklings cause prohibition" which were then abrogated by "five known [sucklings]." Thus, if the aforementioned girl has suckled from the young man's mother five times or more, she is his sister through suckling, and it is not permissible for him to marry her. Otherwise, there is no impediment.