Sunan Ibn Majah Book 25, Hadith 105

“My father told me: ‘I said to ‘Aishah: “I do not think there is any sin on me if I do not perform Tawaf* between Safa and Marwah.” She said: “Allah says: ‘Verily, Safa and Marwah are of the Symbols of Allah. So it is not a sin on him who performs Hajj or ‘Umrah of the House to perform Tawaf between them.’” If the matter were as you say, then it would have said, ‘it is not a sin on him to not perform the Sa’y between them.’ Rather this was revealed concerning some people among the Ansar who previously, when they stated the Talbiyah, they used to recite it for Manat, and it was not lawful for them to perform Sa’y between Safa and Marwah. When they arrived with the Prophet (ﷺ) for Hajj, they mentioned that to him, and Allah revealed this Verse. By Allah, Allah will not accept the Hajj as complete if one who does not perform Sa’y between Safa and Marwah.’”