It is narrated from Hazrat Dhirar bin Azwar that once the Prophet passed by him while he was milking (an animal). The Prophet said: Leave some milk in its udders so that you may obtain it again.
Hadith Referenceمسند احمد / تتمہ مُسْنَدِ الْكُوفِيِّينَ / 18982
Hadith Gradingحکم دارالسلام:حديث ضعيف، خالف فيه الثوري الرواة عن الأعمش