Allah, glorified and exalted is He, created this human race for Himself and laid special claim to it. He created everything for it and on account of it, just as in the divine narration, “Son of Adam, I created you for Myself and I created everything for you. So by My right upon you, do not distract yourself with what I created for you from what I created you for.” 

In another narration, [He said], “Son of Adam, I created you for Myself, so do not play. I guaranteed your provision, so do not toil. Son of Adam, seek Me, you will find Me. If you find Me, you will have found everything while if I eluded you, everything will have eluded you—and I am more beloved to you than everything.” 

He, glorified and exalted is He, made the prayer a connective cause to His closeness, dialogue [with Him], His love, and intimacy with Him.

Ibn Qayyim al-Jawziyyah
Kitâb Asrâr as-Salâh wal-Farq wal-Muwâzanah bain Dhawq as-Salâh was-Samâ’, pgs. 68-69.