It is narrated from Hazrat Salamah bin Qais (may Allah be pleased with him) that the Prophet said to me: When you perform ablution, clean your nose, and when you use stones for istinja, use an odd number of stones.
Hadith Referenceمسند احمد / تتمہ مُسْنَدِ الْكُوفِيِّينَ / 18991