(مالك الدار مولى عمر بن الخطاب) Umar ibn al-Khattab's freedman. He narrated from Abu Bakr and 'Umar.
Khalīlī’s (d.445 ah) comment on Māik ad-Dār:
Malik al-Dar: muttafaq `alayh athna `alayhi al-tabi`un—He is agreed upon (as trustworthy), the Successors have approved highly of him 
Ibn Hajar ‘Asqalānī on Malik ad-Dar:
"Malik ibn `Iyad: `Umar's freedman. He is the one named Malik al-Dar. He has seen the Prophet and has heard narrations from Abu Bakr al-Siddiq. He has narrated from Abu Bakr and `Umar, Mu`adh, and Abu `Ubayda. From him narrated Abu Salih al-Saman and his (Malik's) two sons `Awn and `Abd Allah...Bukhari in his Tarikh narrated through Abu Salih Dhakwan from Malik al-Dar that `Umar said during the period of drought: "O my Lord, I spare no effort except in what escapes my power!" Ibn Abi Khaythama also narrated it in those words but in a longer hadith:The people suffered a drought during the time of `Umar, whereupon a man came to the grave of the Prophet and said: "O Messenger of Allah, ask Allah for rain for your Community." The Prophet appeared to him in a dream and told him: "Go, see `Umar and tell him: You will be watered, and: You must put your nose to the grindstone (`alayk al-kaffayn)!" (The man went and told `Umar.) Then `Umar wept and exclaimed: "O my Lord, I spare no effort except in what escapes my power!"We have also narrated in the Fawa'id of Dawud ibn `Amr and al-Dabbi compiled by al-Baghawi in the narration of `Abd al-Rahman ibn Sa`id ibn Yarbu` al-Makhzumi from Malik al-Dar: he said: "`Umar ibn al-Khattab summoned me one day. He had with him a purse of gold containing four hundred dinars. He said: "Take this to Abu `Ubayda," and he mentioned the rest of the story.Ibn Sa`d mentioned him (Malik al-Dar) in the first layer of the Successors among the people of Madina and said: "He narrated from Abu Bakr and `Umar, and he was known." Abu `Ubayda said of him: "`Umar put him in charge of the dependents in his household. When `Uthman succeeded him, he put him in charge of financial allotments and he was then named Malik of the House."Isma`il al-Qadi related from `Ali ibn al-Madini: "Malik al-Dar was `Umar's treasurer.""
al-Dhahabi, Ibn Hajar, and Ibn Fahd al-Makki consider him a Sahaba.
Malik Ad Dar- Acceptable? http://www.siratemustaqeem.com/phpBB/viewtopic.php?t=3837