With respect to prayer, there are five levels of people. [The lowest] is he 'who wrongs his own soul'; who is remiss; who curtails his ablution and the times, limits and essential elements of prayer.
At the second level is he who keeps the times, rules and elements of prayer; who keeps its ablution but is taken away by distractions, which he lacks the inner strength to resist.
At the third level is he who keeps the limits and essential elements of the prayer, and struggles against distractions. This person is preoccupied with striving against his Foe, 'lest he rob him of his prayer'. In prayer, he is in sacred combat [jihad].
At the fourth level is he who, standing in prayer, completes its requirements, its essential elements and its limits. His heart is absorbed in safeguarding the rules and requirements of the prayer 'lest he miss any of them'. In fact, his entire concern becomes performing the prayer as it should be, completely and perfectly. In this way, his concern for the prayer and for worshipping his Lord absorbs his heart.
At the fifth level is he who, standing in prayer, performs it in the manner of the fourth, but in addition places his heart before his Lord. With this he beholds God - ever vigilant before Him, filled with His love and glory - as if, seeing Him, he were physically present before Him. Therefore, the distractions vanish, as the veil between him and his Lord is lifted. The difference between this person in his prayer and everyone else is as vast as the distance between heaven and earth, for he is occupied [only] with his Lord Almighty in prayer, in which he finds his source of gladness.
[Of these five persons], the first will be punished, the second admonished, the third redeemed, the fourth rewarded and the fifth brought near to his Lord - for his source of gladness has been placed in prayer. And whoever is gladdened by the prayer in this world will be gladdened by nearness to his Lord in this world and the next. He who finds gladness in God, gladdens others [in turn]. But whoever does not, leaves this world a loser.Compiled From:
"The Invocation of God" - Ibn Qayyim al-Jawziyya, pp. 29, 30