277. Observing fast of silence.

Those days, observing a fast by not speaking (speech fasting) was permitted. This verse (19:26) of the Quran says Maryam (AS) observed this kind of fasting.

Taking this as a cue, it should not be misconstrued, this kind of fasting is permissible in Islam. As far as fundamentals are concerned, right from the beginning till the period of Prophet Muhammad the ideology was the same and maintained as such. But it needs to be observed, the laws regarding non fundamentals were not uniform for all communities.

When a law revealed to an earlier community is changed at a later date in the Quran or by Prophet Muhammad, it should be understood as a law specified for that particular community.

Since laws revealed to Prophet Muhammad did not mention silent fast, the need to observe it by the community does not arise.

On hearing about a comrade observing a vow not to talk to anyone, the prophet reprimanded , and restrained him from continuing the same. Hence it needs to be concluded observing a vow not to talk to anyone is not permissible in Islam.

(Hadith Book Bukhari:6704)

To know more on this topic please refer to explanation point 326.