Here's one hadith from Sahih Muslim, where 'Amr ibn Al-'As said:
When Allah put Islam into my heart, I came to the Prophet, may Allah bless him and grant him peace, and said, 'Extend your right hand so that I can offer you allegiance.' He stretched out his right hand and I withdrew my hand. He said, 'What is wrong, 'Amr?' I said, 'I want to make a condition.' He said, 'What is your condition?' I said, 'That I be forgiven.' He said, 'Do you not know that Islam wipes out everything before it and that emigration wipes out everything before it and that the pilgrimage wipes out everything before it?' There was no one I loved more than the Messenger of Allah, may Allah bless him and grant him peace, and no one was more esteemed in my eyes than him. (Sahîh Muslim, Kitâb Al-Îmân, 220)