Tawassul

“The people are in great confusion about the matter of Tawassul and its rulings in the religion, and they greatly differ concerning it, some declaring it lawful and others prohibiting it, some going to extremes and other being over-lenient. Also, a large number of the Muslims have been used to saying in their supplications for centuries such things as: ‘O Allah by the right of your Prophet …,’ or by the right of the sacred house… forgive me.’ `O Allah by the right of me Awliyaa and the pious, and so and so, etc.’ Or `O Allah by the honor of the men of Allah to you, and by the honor of those in whose presence we are, and under whose assistance we exist, relief us and the distressed from all distress’… “So what is Tawassul? What are its types? What is the meaning of the Aayaat and the ahaadeeth, which mention it? And what is the correct ruling for it in Islam?”