It is narrated on the authority of Abu Huraira

We were accompanying the Apostle (ﷺ) in a march (towards Tabuk). He (the narrator) said: The provisions with the people were almost depleted. He (the narrator) said: (And the situation became so critical) that they (the men of the army) decided to slaughter some of their camels. He (the narrator) said: Upon this Umar said: Messenger of Allah , I wish that you should pool together what has been left out of the provisions with the people and then invoke (the blessings of) Allah upon it. He (the narrator) said: He (the Holy Prophet ) did it accordingly. He (the narrator) said: The one who had wheat in his possession came there with wheat. He who had dates with him came there with dates. And Mujahid said: He who possessed stones of dates came there with stones. I (the narrator) said: What did they do with the date-stones. They said: They (the people) sucked them and then drank water over them. He (the narrator said): He (the Holy Prophet) invoked the blessings (of Allah) upon them (provisions). He (the narrator) said: (And there was such a miraculous increase in the stocks) that the people replenished their provisions fully. He (the narrator) said: At that time he (the Holy Prophet) said: I bear testimony to the fact that there is no god but Allah, and I am His messenger. The bondsman who would meet Allah without entertaining any doubt about these (two fundamentals) would enter heaven.