The son of Al-Fudayl b. ‘Ayyad – Allah have mercy on him – said to his father:
“Father! How sweet (beautiful) the speech of the companions is!” 
[Al-Fudayl] said, “Son, do you know why it was so sweet?” 
He replied, “No father, I do not.” 
He [Al-Fudayl] said, “Because they sought Allah the Exalted when they spoke.”



Al-Bayhaqi, Shu’ab Al-Iman 2:299