The Union of God With Man
Nothing escapes Allaah's knowledge, therefore, the wise are those who act accordingly. They feel His presence at all times. They carefully perform all their obligatory (Fard) duties, then they piously try to make up for any of the inevitable deficiencies by doing a host of voluntary acts. These voluntary acts help to protect the obligatory duties. For example, during times of weakness or spiritual lows, one may become lax in fulfilling one's religious duties. However, those who had voluntary practices would likely neglect some of their voluntary practices, while keeping their obligatory duties intact. If they did not have a protective shield of voluntary acts and they fell into a period of spiritual laziness, some of their obligatory duties are likely to be discarded or neglected. The more someone strengthens his obligatory practices by performing voluntary acts, the more his life conforms to the Sharee'ah, the will of Almighty Allaah. Allaah conveyed this principle through the Prophet 
in a Hadeeth saying: "The most beloved thing with which My slave may come close to me is that which I have made obligatory (Fard) on him. My servant will continue to come closer to me by voluntary acts (of worship) until I love him. If I love him, I will be his hearing by which he hears, his sight by which he sees, his hand by which he grasps, and his foot by which he walks. If he asks Me anything I would give it and if he seeks refuge in Me I would protect him."137
This Walee of Allaah would only hear, see, grasp and walk to what is Halaal (lawful), while conspicuously avoiding all the Haraam (prohibited) as well as that which leads towards it. This is the only true goal worthy of dedicating one's life. Its attainment is the perfection of man's dual role as servant of God and governor of the world. But, it cannot be reached except by the route prescribed in the Hadeeth. First the compulsory duties have to be completely established, then the prescribed voluntary acts of worship have to be performed consistently and according to the Sunnah. Allaah emphasized this fact by telling His Prophet to inform the believers:
"Say, if you love Allaah, follow me (Muhammad) and Allaah will love you."138
Therefore Allaah's love can only be attained by strictly following the directives (Sunnah) of His Apostle and by carefully avoiding all innovations in religious matters. This formula is contained in the following Hadeeth in which the Prophet was reported by Abu Najeeh to have said, "Keep to my Sunnah and that of the rightly guided caliphs. Bite on to it with your molars. And beware of innovations, for verily they are all heresy (Bid'ah) and heresy is misguidance which leads to the hellfire."139
One who strictly follows this principle will only listen to what Allaah wishes for him to listen to. For Allaah said describing the righteous:
"And when the ignorant (mockingly) address them, they merely say: 'Peace'"140
Elsewhere in the Qur'aan He also said,
"He has already revealed to you in the Book, that when you hear the signs of Allaah denied and ridiculed, you should not sit with them unless they change the subject. If you did you would be like them."141
By him listening only to what Allaah wishes for him to hear, Allaah has metaphorically become his hearing. In a similar way, Allaah becomes his sight, hands and feet.
This is the correct interpretation of the previously mentioned Hadeeth in which Allaah states that He will become man's hearing, sight, hands and feet. Unfortunately, this Hadeeth has been misinterpreted by mystics as support for the concept of union with Allaah - May Allaah forbid.