Imaam Maalik (rahimahullaah) was asked about a Mas’alah (an affair of the religion), so he said, “I don’t know.” Then it was said: “Indeed, it is a light and simple affair!!” So he became angry and said: “There is nothing light in knowledge, and have you not heard the statement of Allaah (The Most High): [إِنَّا سَنُلۡقِى عَلَيۡكَ قَوۡلاً۬ ثَقِيلاً-Verily, We shall send down to you a weighty Word (i.e. obligations, legal laws, etc. (73:5)] All (affairs) of knowledge are heavy, especially that which one will be questioned about on the Day of Judgement.
[Fadlul Ilm pages: 541-542]