Hazrat Abu Bakhtari narrates that in the time of the Holy Prophet (peace and blessings be upon him), there was a woman who used to fast but did not guard her tongue. When the Messenger of Allah (peace and blessings be upon him) came to know of this, he said that her fast was not valid. When she began to guard her tongue, he said that soon her fast would become valid. When she guarded it even more, he said that now her fast was valid.