He who abstains from the enjoyments of the world, even its wholesome ones, is called a zahid (ascetic); and he who is careful to perform worship, prayer and fasting and the like, is called an 'abid (devotee); and he who keeps his thought turned perpetually towards the realm of light in order that the light of the Real shine in his breast is called an 'arif; and sometimes two or more of these epithets may apply to the same person.
Although Ibn Sina defines here the zahid, the 'abid and the 'arif, yet at the same time he is defining zuhd, 'ibadah, and 'irfan. This is because a definition of zahid, 'abid, or tarif per se includes implicitly a definition of zuhd, 'ibadah, or 'irfan. Thus the conclusion to be drawn from this passage is that zuhd is abstinence from worldly enjoyments; 'ibadah is the performance of specific acts like prayer, fasting, reciting the Quran and the like; and 'irfan is turning away the mind from everything but Allah and paying complete attention to the Divine Essence so that the light of the Real may shine on one's heart.
The last clause indicates an important point. One or more of these characteristics may occur in combination. Thus it is possible for an individual to be an 'abid and a zahid, a zahid and an 'arif, an 'abid and an 'arif, or an 'abid, zahid, and 'arif at one and the same time. Ibn Sina has not elaborated this, but he implies that although it is possible for one to be a zahid or an 'abid and not be an 'arif, it is not possible for one to be an 'arif and not be a zahid and an 'abid. One may be both a zahid and an 'abid without being an 'arif, but an 'arif by definition is also a zahid and an 'abid. So, although not every zahid or 'abid is an 'arif, every 'arif is a zahid and an 'abid.
In the next passage we will see that the zuhd of an 'arif differs in its goal from that of a non-'arif. In fact, the spirit and essence of the 'arif's zuhd and 'ibadah are different from those of the non-'arif:
The zuhd for the non-'arif, is a transaction by which he gives up the pleasures of the world for the pleasures of the Hereafter, whereas for the 'arif it is something through which he dissociates himself from everything that keeps him from attention towards God and he looks down on everything except God. Whereas worship for the non-'arif is a transaction by which he performs actions in the world for a reward (ajr, thawab) to be received in the Hereafter, for the 'arif it is a kind of exercise that is aimed at strengthening his self's intellectual and imaginative faculties, and which, by repetition, draws away the self from the realm of illusion to the realm of the Real.