As against this, three rulers emphasised their own importance. Balban
  used to say that after the Prophet the most important office was that of the
  sovereign and called himself the ‘Shadow of God’. Muhammad bin
  Tughluq assumed this style during the early years of his reign and
  although Balban had retained the name of the caliph in the khutba and
  sikka, Muhammad made no mention of caliph anywhere. But, despite all
  this, neither of them had the audacity to call himself the caliph. The only
  person who had done this was Qutub-ud-din Mubarak Khalji.
      But only three Sultans sought, and secured a mansur or letter of
  investiture from the caliph. The first among them was Iltutmish. Next
  Muhammad bin Tughluq tried to pacify the ulema by securing an
  investiture from the Abbasid caliph in Egypt. After him Firoz also sought
  and secured it twice.
      The real object of honouring the office of the caliph is interesting.
  Muslims in general regarded it as incumbent on the Sultan to show respect
  to the caliph, and opposition to the Sultan, who had been recognised by
  the caliph as his deputy, was regarded as contrary to the Holy Law. Hence
  the Sultans kept up the pretense of subservience to the caliph just to
  exploit the popular Muslim sentiment in their favour.
Law of Succession According to Islamic ideals, essential attributes of a
sovereign required that he should be a male adult, suffering from no physical
disability, a freeborn Muslim, having faith in Islam and acquainted with its
doctrines, and he should be elected by the people.
     However in practice there were several violations of the prescribed
criteria for being elected to the throne. Raziya was raised to the throne despite
her womanhood. Minority proved no bar in the case of Muhammad bin
Tughluq. Qutub-ud-din Aibak’s authority was recognised even before his
manumission. Kaiqubad remained the Sultan as a paralytic. Nasir-ud-din
Khusrau had no special reverence for Islam and yet he was accepted as the
Sultan of Delhi. Ala-ud-din Khalji frankly admitted his ignorance of the
sharia but nobody dubbed him as unfit to rule on that score. As far as
election was concerned, it had never existed in Islam. At best, support of a
few leading men was regarded