It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him) that he heard the Messenger of Allah (peace and blessings be upon him), while he (peace and blessings be upon him) was riding his she-camel al-Jad'a and Sayyiduna al-Fadl bin Abbas (may Allah be pleased with them both) was behind him (peace and blessings be upon him), say: "Do not make (sworn) presumptions against Allah, do not make presumptions against Allah, for whoever makes such a presumption against Allah, Allah will prove him a liar."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7867