The Kalifah is chosen by Ahlul Ikhtiar, and the requirements of the Kalifah are the following:
Must be Muslim
Must be Mature
Must be Sane
Must be a freeman and not a slave
Must be knowledgeable
Must be Righteous
Must be a Male/Man
Have prudence in opinion/ Wisdom
Must have firm qualities, like bravery and fairness
Must have a healthy body and strength
Must not have extreme care or want for the position
إِنَّا وَاللَّهِ لاَ نُوَلِّي عَلَى هَذَا الْعَمَلِ أَحَدًا سَأَلَهُ
وَلاَ أَحَدًا حَرَصَ عَلَيْهِ
We do not appoint to this position one who asks for it nor anyone who
is covetous for the same
صحيح مسلم (Sahih Muslim 1733 c)
- Must be from Quraish
إِنَّ هَذَا الأَمْرَ فِي قُرَيْشٍ، لاَ يُعَادِيهِمْ أَحَدٌ إِلاَّ
كَبَّهُ اللَّهُ عَلَى وَجْهِهِ، مَا أَقَامُوا الدِّينَ
Authority of ruling will remain with Quraish, and whoever bears
hostility to them, Allah will destroy him, as long as they abide by
the laws of the religion
صحيح بخاري (Sahih al-Bukhari 3500)
Sources: al-eman.com