Riyad as-Salihin, Book 1, Hadith 373 (In-Book) ⓘ

'Umar bin Al-Khattab (May Allah be pleased with him) reported: I sought permission of the Prophet to perform 'Umrah. He granted me leave and said, "Dear brother! Do not forget us in your supplications". ('Umar added): This is something I would not exchange for the whole world.Another narration is: He said, "Include us, my dear brother, in your supplications." [Abu Dawud and At-Tirmidhi, who categorized the Hadith as Hasan Sahih. Sheikh Salim Al-Hilali in his book "Bahjatun-Nazireen, Sharh Riyad-us- Saliheen" classifies it as "Da'if", the reason being that 'Asim bin 'Abdullah is "weak" in narration].

وعن عمر بن الخطاب رضي الله عنه قال‏:‏ استأذنت النبي صلى الله عليه وسلم في العمرة، فأذن لي، وقال‏:‏ ‏"‏لا تنسنا يا أخي من دعائك‏"‏ فقال كلمة ما يسرني أن لي بها الدنيا‏.‏ وفي رواية قال‏:‏ ‏"‏أشركنا يا أخي في دعائك‏"‏‏.‏ حديث صحيح ‏(‏‏(‏رواه أبو داود، والترمذي وقال‏:‏ حديث حسن صحيح‏)‏‏)‏‏.‏