The Sahaba's Importance of Ich Tihad

The Sahaba made ich tihad about firk even during the lifetime of the Prophet Salaamu alayhi wa sallam. Ahmad ibn Yasser when he fell Junub in the desert and he did not have any water what did he do? He said well if we do tihamum for wudu I guess we're gonna have to do tihamm for rusud as well. This shows us the legal permissibility of extrapolating what we know of the Quran and Sunnah to cater to a situation that the Quran does not tell us about. The basis of our religion being applicable and all times and place through the medium of ich t