Staying seven days in the home of someone who rejects the Vajrayana.
We incur this downfall if without a good reason we stay for more than seven days in the home of a person who is critical of the Vajrayana.
The logic behind this is fairly straightforward. We are by nature social creatures, and so we naturally become socialized into the views of those around us. This happens almost automatically, as if by osmosis. Of course, if we are mindful, it is possible to avoid this affect, but most of us are rarely sufficiently mindful. Because of this socialization effect, we are advised to avoid those who are critical of the Dharma, in particular the Vajrayana path, and to instead choose to spend as much time as we can with those who embrace the path. In this way we protect ourselves from sub-consciously taking on board their critical views and assumptions, and instead willingly socialize ourselves into a Dharma way of looking at the world.
The second reason why we want to avoid this is to protect those who are critical. It can happen that people are so adverse to our practice that our very presence is a constant reminder of it. In such a situation, every time they see us – even if they say nothing to our face – they create an endless series of negative karma of rejecting the Dharma by our being around. In order to protect them from creating such karma we try not to stay too long.
Sometimes this can pose a problem for us when we go home to visit our family during the holidays, for example, if they are hostile to our practice. If we do find ourselves in such a situation and it would be karmically inappropriate for us to not visit our family, we should just strive to be mindful when we are home. If we are seen to be avoiding them, and they are aware it is because of our practice, then even our absence is a form of presence and we incur a similar downfall. For example, if we are normally there for Thanksgiving in the U.S., but then we are not because of our practice, even though we are not there our mere absence itself will be seen, and that absence will be understood as “it is because they have gone off and joined some cult, and now they don’t even come home.” So we need to be skillful. Normally, though, if we do not flaunt our practice and rub our relatives noses in it, they are unlikely to actively oppose it and we should be OK.