Narrated Abu Dhar:
We were in the company of the Prophet on a journey and the Mu’adhin wanted to pronounce the Adhaan for the (Zuhr) prayer. The Prophet said to him, “Let it become cooler.” Then he again wanted to pronounce the Adhaan but the Prophet; said to him, “Let it become cooler.” The Mu’adhin again wanted to pronounce the Adhaan for the prayer but the Prophet said, “Let it become cooler,” till the shadows of the hillocks become equal to their sizes. The Prophet added, “The severity of the heat is from the raging of Hell.”
More on delaying the Zuhr prayer here.
Narrated Malik bin Huwairth:
Two men came to the Prophet with the intention of a journey. The Prophet said, “When (both of) you set out, pronounce Adhan and then Iqama and the oldest of you should lead the prayer.”
Even if two people form a group/team, one of them should be the leader/Imaam/ameer.
We came to the Prophet and stayed with him for twenty days and nights. We were all young and of about the same age. The Prophet was very kind and merciful. When he realized our longing for our families, he asked about our homes and the people there and we told him. Then he asked us to go back to our families and stay with them and teach them (the religion) and to order them to do good things. He also mentioned some other things which I have (remembered or) forgotten. The Prophet then added, “Pray as you have seen me praying and when it is the time for the prayer one of you should pronounce the Adhan and the oldest of you should lead the prayer.
More on choosing the Imaam here.
Once in a cold night, Ibn ‘Umar pronounced the Adhan for the prayer at Dajnan (the name of a mountain) and then said, “Pray at your homes”, and informed us that Allah’s Apostle used to tell the Mu’adin to pronounce Adhan and say, “Pray at your homes” at the end of the Adhan on a rainy or a very cold night during the journey.”
More on praying at homes here.
Narrated ‘Aun bin Abi Juhaifa:
My father said, “I saw Allah’s Apostle at a place called Al-Abtah. Bilal came and informed him about the prayer and then came out with an Anza and planted it in front of Allah’s Apostle at Al-Abtah and pronounced the Iqama.”
More on Sutrah here.