Reference: al-Jaami’ li-Hayaat al-‘Allaamah Muhammed ibn Saalih al-Uthaymeen – Page 25
It has been narrated:
When the Shaykh was in need of refilling his pen with ink from an ink pot in the University library to use for University work purposes, he would make sure to empty the ink out of his pen into the ink pot before he left, since it was the property of the University.