Views of Umar regarding one who has no water for ablution

In his Saheeh, Muslim, in the chapter of Dry Ablution (Tayammum), has narrated through four chains of narrators from Abdur Rahman bin Abza that:

“Abdul Rahman bin Abza narrated it on the authority of his father that a man came to Umar and said: I am (at times) affected by seminal emission but find no water. He (Umar) told him not to pray. Ammaar then said. Do you remember, O Commander of Faithful, when I and you were in a military detachment and we had a seminal emission and did not find water (for taking bath) and you did not say prayer, but as for myself I rolled in dust and said prayer, and (when it was mentioned before) the Messenger of Allah (s.a.w.a.) said: It was enough for you to strike the ground with your hands and then blow (the dust) and then wipe your face and palms.

 Umar said: Ammaar, fear Allah. He said: If you so like, I would not narrate it.”

 (Saheeh Muslim, [1/355, H. 112]; Kitabul Haiz; Musnad Ahmad, 4:265 [5/329, H. 1786])