روى البخارى عن ابى هريرة عن النبى انه قال: انما سمى الخضر لانه جلس على فروة بيضاء فاذا تهتز من خلفه خضراء
Al Bukhari reports from Abu Hurairah that the Prophet salla Llahu ‘alayhi wa sallam said, “Khidr was given his name because he sat upon a white skin. Suddenly, whatever was behind him turned lush and green.”
ولدينا من مثل هذه الاحاديث ما يملا كتابا براسه وتراجع احاديثه التى تلقاها عن استاذه كعب الاحبار فى مكانها من هذا الكتاب
We have a great number of this kind of ahadith, such that it can fill an entire book. You can refer to the ahadith which he learnt from his teacher, Ka’b al Ahbar, in its appropriate place in this book.
Our comment: We will reproduce the ‘authentically established ahadith of the Ahlul Bayt, which is narrated by them from their grandfathers.’ Al Saduq reports from Abu al Hassan ‘Ali ibn Musa al Rida rahimahu Llah:
لما قبض رسول الله اتاهم ات فوقف على باب البيت فعزاهم به اهل البيت يسمعون كلامه ولا يرونه. فقال على (ع): هذا هو الخضر (ع) اتاكم يعزيكم بنبيكم
When the Prophet salla Llahu ‘alayhi wa sallam passed away, a stranger came to them and stood at the door of the house. He offered his condolences to them regarding him. The Ahlul Bayt heard his speech, but they could not see him. ‘Ali said, “This is Khidr, he came to you to offer you condolences regarding your Prophet.”
وكان اسم الخضر خضرويه بن قابيل بن ادم وانه انما سمى الخضر لانه جلس على ارض بيضاء فاهتزت خضراء فسمى الخضر لذلك…و قد اخرجت الخبر فى ذلك مسندا فى كتاب علل الشرائع والاحكام والاسباب
The name of Khidr was Khudruwayh ibn Qabil ibn Adam. He is also referred to as Khudrun as well as Ja’d. the only reason why he is called Khadir is because he sat upon a white piece of land which turned lush and green. That is why he is called Khidr… The complete narration with its chain is reported in the book ‘Ilal al Shara’i’ wa l-Ahkam wa l-Asbab.
 Ikmal al Din, pg. 362 # 6.
 Refer to Bihar al Anwar, 64/291, 13/303 # 24; Al ‘Ilal, chapter 54, Tafsir al Safi, 3/251, Nur al Thaqalayn, 3/273, 276, al Mizan, 13/352, Majma’ al Bayan, 6/483, al Tibyan, 7/70.