Is it permissible for the paternal male cousin to marry a girl who was nursed by his mother for one night, with the number of sucklings unknown?

The most authoritative opinion is that the prohibitive suckling consists of five known sucklings within the first two years (of the child's life), and anything less than that does not establish prohibition. However, it is preferable for the paternal cousin not to marry the girl as a precautionary measure, to clear one's conscience, and to avoid ill-repute. This is in accordance with the Prophet's (peace be upon him) saying to Uqbah ibn Al-Harith: "How can you [marry her] when it has been claimed?" and also the saying: "Whoever guards against doubtful matters has indeed cleared himself in his religion and his honor."