“The greatest way to achieve happiness is through Tawḥīd. The happiness of a person’s heart depends upon its perfection, strength and increase.”
Tawḥīd can weaken and strengthen in the servant’s soul and it can increase and decrease. This is because the basis of Tawḥīd is belief in Allāh and singling Him out with all worship and to single Him out with His names and attributes, along with singling Him out with His lordship. And the people are of different levels in their actualization of this Tawḥīd. Therefore, the happiness of a person depends upon the perfection of this Tawḥīd, its strength and increase. This is something that every person acknowledges about his own self: an increase in Īmān and decrease in Īmān, the strength of Īmān and the weakness of Īmān and the strength of Tawḥīd and the weakness of Tawḥīd. If a person was to scrutinize his condition at all times, then he would recognize this.”