Abdullah bin Abbas reported,

Umar bin Khattab was asked, "Tell us about the campaign of hardship."He said, "We set out for Tabuk during a severe heatwave. We camped at a place where thirst overcame us so badly that we thought our necks would be cut off. A man would go off searching for water and not return until we thought his neck would be cut off. A man would even slaughter his camel, squeeze out the contents of its stomach, drink the liquid, and place what remained on his liver to cool it.Abu Bakr al-Siddiq said, 'Messenger of Allah, Allah has accustomed you to good responses when you supplicate, so pray for us.'He replied, 'Would you like that?'Abu Bakr said, 'Yes.'So he raised his hands ﷺ, and he did not lower them until a cloud cast its shade over us and poured down rain. The people filled whatever vessels they had with water. Then we went to see how far the rain had reached, and we found that it had not extended beyond the camp."

Azami 12524

Sahih

عن عبد الله بن عباس

أنه قيل لعمر بن الخطاب: حدثنا من شأن العسرة، قال: خرجنا إلى تبوك في قيظ شديد، فنزلنا منزلا أصابنا فيه عطش، حتى ظننا أن رقابنا ستنقطع، حتى أن الرجل ليذهب فيلتمس الماء، فلا يرجع حتى نظن أن رقبته ستنقطع، حتى أن الرجل لينحر بعيره، فيعصر فرثه، فيشربه ويجعل ما بقي على كبده، فقال أبو بكر الصديق: يا رسول الله! قد عودك الله في الدعاء خيرا، فادع لنا، فقال: أتحب ذلك؟ قال: نعم، فرفع يديه ﷺ، فلم يرجعهما، حتى أظلت سحابة، فسكبت، فملؤوا ما معهم، ثم ذهبنا ننظر، فلم نجدها جاوزت العسكر.

الأعظمي 12524صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Tafsir of the great Quran
Chapter
Virtues of Surah Baqarah
Section
His saying, "Allah has already forgiven the Prophet and the Muhajirun and the Ansar who followed him in the hour of difficulty after the hearts of a party of them had almost inclined to doubt, and then He forgave them. Indeed, He is Kind and Merciful to them." And upon the three who were left behind, until when the earth became strait for them despite its vastness, and their own souls became strait for them, and they were certain that there is no refuge from Allah except in Him, then He turned to them so that they might repent. Indeed, Allah is the Accepting of repentance, the Merciful
Numbering
Jami al-Kamil 12524 (2nd edition)
Azami 12524