Musannaf Ibn Abi Shayba 17:1209

Abu Bakr narrated to us, he said: Yazid ibn Harun narrated to us, he said: Ash'ath ibn Siwar informed us, from Kardus, from Abdullah, who said: "Indeed, hearts have periods of energy and receptiveness, and indeed they have periods of turning away and withdrawal. So, speak to the people while they are receptive to you."