Sultan Alā ad-Dīn Kayqubād the Seljuq Sultan of Rûm in Ertugrul.
Ibn Kathir said:
صاحب الروم كيقباذ الملك علاء الدين
صاحب بلاد الروم، كان من أكابر الملوك وأحسنهم سيرة، وقد زوجه العادل ابنته وأولدها، وقد استولى على بلاد الجزيرة في وقت وأخذ أكثرها من يد الكامل محمد، وكسر الخوارزمية مع الأشرف موسى رحمهما الله.
Ruler of al Rum Kayqubād Malik Ala ud din he was among great Kings who had good seerah, Adil married his daughter with him and they had children. He captured the city al Jazeera at a time and took major part of it from the hands of al Kamil Muhammad and shattered al Khawarzmiya with al Ashraf Musa, May Allah have mercy on him.
[al Bidaya wal Nihaya vol 13 under 634 h]