Is it permissible to sing in isolation or in front of sisters if the lyrics do not contain obscenities?

There is no objection to singing (melodious recitation of metrical speech) if it is devoid of musical instruments and forbidden words, and not in the presence of a non-mahram (definition). Ibn ‘Uthaymin mentioned the permissibility of listening to singing that is free from music and other musical instruments, provided that it does not contain anything that causes temptation, and that it does not divert a person from what is obligatory upon him.