On the authority of Jurthum bin Nashir (may Allah be pleased with him) that the Messenger of Allah (peace be upon him) said:

Verily Allah the Almighty has laid down religious obligations (fara'id), so do not neglect them. He has set boundaries, so do not overstep them. He has prohibited some things, so do not violate them; about some things He was silent, out of compassion for you, not forgetfulness, so seek not after them.

[Daraqutni]