"And devote your attention tot he heart and your inner state. Indeed he, upon whom be peace, said: 'Allah does not look at your faces and your deeds. He only looks to your hearts and your intentions.'
Make your words a reality through your action. Make your actions a reality through your intention and your sincerity. Make your intention and your sincerity a reality through the purification of your inner being and the soundness of your heart, for your heart is your cardinal point around which all else revolves.
It has been narrated in tradition: 'Beware! In the body is a morsel of flesh when it is sound, the whole body follows suit and becomes sound; and when it sickens, the body sickens likewise. Indeed it is your heart!'
It is an obligation to take care of the heart and to exert an effort to its health and to strengthening it. The heart, known in Arabic as the qalb, is susceptible to perturbation, turning and change, known in Arabic as al-taqallab so much so that he, upon whom peace said: 'It changes much faster than the cooking pot as it boils.' And he, upon whom be peace of Allah, used to frequently supplicate thus: 'O Changer of hearts, hold my heart steadfastly upon your religion.' And used to say: 'Hearts are in the finger-clasp of the All-Merciful One. If He wills, He holds them steadfastly upon righteousness. And if He wills, they go astray from it.' And when He, upon whom be peace wanted to be emphatic in an oath, he would say: 'No, in the Name of He who changes hearts.'
The Exalted said the Prophet Ibrahim, His Friend (Khalil) said:
"[And let me not be in disgrace] on the Day when (men) will be raised up, the Day when neither wealth nor sons will avail, but only he (will prosper) that brings to Allah a sound heart."
Show the utmost concern – may Allah show you mercy – to come to your Lord with a heart sound and free from associating partners, hypocrisy, innovation, vile characteristics like arrogance, ostentation, envy and dishonesty towards the Muslims and vices of that nature. Seek Allah's assistance and be steadfast. Work hard and exert yourself and say often:
"Our Lord! Let nor our hearts deviate now after Thou hast guided us, but grant us mercy from Your own Presence; for You are the Grantor of bounties without measure."