The Secret of Salaah

Sheikh-ul-Islaam Ibnul-Qayyim Al-Jawziyyah رحمه الله stated:

The secret of the Salaah, its soul and core is the slave’s turning to Allaah in totality whilst in the prayer. Therefore, just as it is not befitting that he turns his face away from the Qiblah to other than it during the Salaah, it is likewise not befitting to turn his heart away from his Lord to other than Him during the Salaah. Rather he (the slave) makes the Kaa’bah, which is the house of Allaah, the Qiblah of his face and body. (Likewise) he makes the Lord of the House the Qiblah of his heart and soul. So according to how much the servant turns to Allaah in his Salaah, (then this) will determine how much Allaah turns towards him. And if he (the slave) was to turn away, then Allaah will turn away from him. 

And (the saying goes): 

“.... as he lives, he is treated (accordingly).”

{Source: Asraarus-Salaah, pg. 75}