How can a Muslim contemplate Tasbeeh (glorification), Tahleel (exaltation of God), and Istighfar (seeking forgiveness), and what should he bring to mind to combine the remembrance of the tongue with the remembrance of the heart?

Recalling the meanings of the remembrances (dhikr) and contemplating them helps to increase faith. The most perfect dhikr is that which is done with both the heart and the tongue. When glorifying (tasbeeh), the servant recalls Allah's transcendence above imperfections and His attribute of perfection. Thus, glorification includes both transcendence and magnification. When declaring "La ilaha illallah" (tahlil), the servant recalls the singularity of Allah's divinity and that He alone is worthy of worship. When seeking forgiveness (istighfar), the servant recalls the enormity of his sins and his humble plea to Allah to forgive them, while also recalling that Allah is Forgiving and Merciful. And so it is with all remembrances; one must bring the heart to presence and feel their magnificent meanings.