Hudhaifah (رضي الله عنه) said: “We were sitting down in the company of the Prophet (صلى الله عليه) when he said:

إني لا أدري ما قدر بقائي فيكم فاقتدوا باللذين من بعدي وأشار إلى أبي بكر وعمر

“Verily, I do not know how much longer I will be among you, so follow those who come after me.” And he (صلى الله عليه) then pointed in the direction of Abu Bakr (رضي الله عنه) and ‘Umar (رضي الله عنه)”

Ibn Majah