Assalaamu alaykum. Please answer this question: can you tell me the soundness of the following hadith?
Ibn Abi Ad-Dunya relates the following from Ka’b:
“Ibrahim (Abraham), peace be upon him, saw a man in his house and asked, ‘Who are you?’ He replied, ‘I am the Angel of Death.’ Ibrahim said, ‘If you really are him, then show me a sign by which I can be sure that you are the Angel of Death.’ The Angel of Death said, ‘Turn your face,’ so [Ibrahim] did so, and when he turned back around, he saw the form [of the Angel] when he takes the souls of the believers. He saw from the light and the splendour the like of something only truly Allaah Most High knows. Then [Ibrahim] was told, ‘Turn your face again,’ so he did so. Then he turned around and saw the form [of the Angel] when he takes the souls of the disbelievers and the sinners, upon which Ibrahim was absolutely terrified, with his whole body trembling [out of fear] and collapsing on the ground as though his life was taken out of him.” [As-Suyuti, Al-Haba’ik fi Akhbar Al-Mala’ik, p.17.
In other places, I hear descriptions of him in both forms; that itself is also confusing. Can you inform me of the soundness of the hadith as well as of the attribution of these characteristics to the Angel of Death?

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger. 

The story that you mentioned is not a hadeeth from the Prophet ; rather, it is one of the Israelite stories narrated by Ka’b Al-Ahbaar, who was one of the Taabi’een (the generation that followed that of the Companions).

Others have also narrated stories of the coming of the Angel of Death to Ibraaheem (Abraham), may Allah exalt his mention.

Ibn Katheer said in Al-Bidaayah wan-Nihaayah, “Ibn ‘Asaakir narrated the stories of the People of the Book about the coming of the Angel of death to Ibraaheem, may Allah exalt his mention, from many righteous predecessors; only Allah knows whether they are true or false.”

Such stories are neither believed nor disbelieved.

Al-Bukhari narrated in his Saheeh from Abu Hurayrah, may Allah be pleased with him, “The people of the Scripture (Jews) used to recite the Torah in Hebrew and explain it in Arabic to the Muslims. So the Messenger of Allah said, ‘Do not believe the people of the Scripture nor disbelieve them, but say: {We have believed in Allah and what has been revealed to us.} [Quran 2:136].’”

As regards being confused, you should know, dear brother, that the Shariah might come with something that people do not easily understand, but the Shariah does not come with something that is impossible.

Indeed, there is in Islamic faith what dazzles the mind as well as matters that a person does not easily understand, such as the matters of the Unseen, like the torment of the grave and its bliss, the Siraat (the bridge over the Hellfire), the Basin, Paradise and Hell, and other matters of the Unseen; the mind is bewildered in trying to understand the reality of these matters and how they are because they have no likeness in our worldly life so that we may understand what they really are.

Ibn Abil-Izz said in Sharh At-Tahaawiyyah about the torment of the grave, “The mind cannot grasp how these matters are because it does not know their likeness in this worldly life. But the Shariah does not come with something that is impossible for the mind to believe; rather, it may sometimes come with something that the minds get bewildered about...”

The same thing applies to the description of the angels which the Islamic texts stated, such as them having two wings, three wings, four wings, and more; and the fact that Jibreel (Gabriel), may Allah exalt his mention, has six hundred wings; and the fact that the angels of death come to the believers with white faces like the sun, while they come to the non-Muslims with dark faces; and other descriptions - all of which are matters of the Unseen which we must believe in.

Allah knows best.