The first to build the Quba Mosque was Ammar bin Yasir (may Allah be pleased with him)

It is narrated from al-Hakam bin Utaybah that when the Messenger of Allah (peace and blessings be upon him) first came to Madinah, Sayyiduna Ammar bin Yasir (may Allah be pleased with him) said: It is essential that the Messenger of Allah (peace and blessings be upon him) have a place where, after his midday rest, he (peace and blessings be upon him) can take shade and offer prayer. So Sayyiduna Ammar (may Allah be pleased with him) gathered stones and built the Mosque of Quba. Thus it is the first mosque that was built, and Sayyiduna Ammar (may Allah be pleased with him) built it.

It is narrated from al-Qasim bin Abd al-Rahman that the first person to build a mosque in which prayer was offered was Sayyiduna Ammar bin Yasir (may Allah be pleased with him).

It is narrated from Asim bin Umar, concerning the names of those Companions among the Muhajirun and the Ansar between whom the Messenger of Allah (peace and blessings be upon him) established brotherhood (mu'akhah), that he said: The Messenger of Allah (peace and blessings be upon him) established brotherhood between Sayyiduna Ammar bin Yasir and Sayyiduna Hudhayfah bin al-Yaman (may Allah be pleased with them both). Abdullah bin Ja'far said: Although Sayyiduna Hudhayfah (may Allah be pleased with him) was not able to take part in Badr, his Islam was very early. And they all agree that Sayyiduna Ammar bin Yasir (may Allah be pleased with him) took part in Badr, Uhud, the Trench (Khandaq) and all the battles alongside the Messenger of Allah (peace and blessings be upon him).