Shaikh Khalil Ahmad Saharanpuri (may Allah have mercy on him) said,

‘The aim and objective of spiritual path (sulook) is to make the heart of the seeker yearn for Allah’s pleasure  similar to the body’s demand for food. That is, the desire to worship becomes similar to the craving for food and water.

This can only happen when the his heart is,

-  filled to the brim by the majesty and love of Allah and

- empty from the desires of all that is other-than-Allah (ma-siwa Allah)

Until this love of other-than Allah exists, to the extent that it resists the love and awe of Allah, one  can not be true in his search for the Divine pleasure and be able to abstain from all sinful activities thoroughly.

In summary, two things are essential. Firstly,  cleansing the heart (takhliya) from all that is ’other’ (-than-Allah) and finally adorning (tajeliya) it with the  love and awe of Allah.

Successful accomplishment of these two things results in bestowment of (spiritual) illuminations and other honors from Allah. This is known as taheliya.