Sometimes, exactly at the time of someone's arrival, the power goes off, and it is said, "The power went off because you came." This is a bad omen, which is not permissible in Shari'ah. Similarly, when the power comes back on while saying something, it is said that the statement is true, that is why the power came back on. This is a good omen, which is permissible in Shari'ah. (Aham Masail / Vol: 3 / Page: 38)