Musnad Abu Ya'la al-Mawsili 160:208

And with his chain of narration, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Do not sit in the thoroughfares nor in the courtyards." They said: "O Messenger of Allah, we cannot avoid that." He said: "If you must, then give them their right." They said: "O Prophet of Allah, and what is their right?" He said: "Returning the greeting, lowering the gaze, responding to the one who sneezes, and guiding the way."