Self mastery is gained by:
1) Fasting
2) Prayer
Allah Most High says:
“O believers fasting has been prescribed for you as it was prescribed for those aforetime that you may gain taqwa…When my servants ask you concerning Me I am indeed close to them; I respond to the supplication of the supplicant when he calls on Me. They should listen to Me and believe in Me that they may tread the righteous path.” (2: 183-186)
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