1. Rebbi Shimon ben Yochai: A person who does any one of five things puts himself in grave danger.
2. An evil spirit rests on peeled garlic, an onion, and an egg that are left out overnight.
3. A woman who steps on a discarded fingernail risks losing her pregnancy.
4. If a man lets blood and then has relations, he causes any future children from those relations to be weak.
5. One should not have marital relations during the day.
A BIT MORE
1. These things include: eating peeled garlic, an onion, or an egg that was left out overnight, drinking a diluted drink left overnight, sleeping in a graveyard, cutting one's nails and throwing them away in the public domain, and letting blood and then having relations.
2. However, if some of the peel or "hairs" on the garlic or onion remain, there is no danger.
3. A devoutly pious person burns his nails. A righteous person buries them. An evildoer carelessly throws them away (in an area where women may step on them; see Moed Katan 18a).
4. The children will be exceptionally weak if both the man and woman let blood before having relations. However, if they eat after letting blood and before having relations, this does not apply.
5. One reason is that the man may see something unsightly in his wife that will make him scorn her.