Musnad Ahmad 850:0

Narrated ‘Abd al-Rahman ibn Samurah: The Messenger of Allah (ﷺ) said to me: "O ‘Abd al-Rahman ibn Samurah, do not ask for leadership. For if you are given it because you asked for it, you will be left to it (to manage it on your own), but if you are given it without asking for it, you will be helped with it." And he said: "If you take an oath to do something, then see something else better than it, then do that which is better, and make expiation for your oath."