The fact of the matter is that in a state of salah [i.e. being sound or pious], it is incumbent upon man to be pure from every kind of corruption, whether it be in relation to doctrines or deeds. For example, a person’s body is healthy when all its primary constituents are in their normal state, and there is no excess or deficiency. If even a single constituent abnormally increases, the body becomes ill. Similarly, the health of a person’s soul depends upon an equilibrium. It is this very equilibrium which is alluded to in the Holy Quran by the term al-sirat-ul-mustaqim [i.e. the right path]. In a state of salah, a person becomes wholly devoted to God, as was the case with Hazrat Abu Bakr Siddiqra. Gradually, a salih [or a virtuous person] progresses until they attain to a station of rest and it is here that they experience “the expansion of their breast”, just as the Messenger of Allah, peace and blessings of Allah be upon him was addressed:
اَلَمْ نَشْرَحْ لَکَ صَدْرَکَ
‘‘Have We not opened for thee thy bosom.”
It is beyond me to express in words this state of “the expansion of the breast.”
(Hazrat Mirza Ghulam Ahmadas, Malfuzat, Vol. 1, pp. 193-194)