Where mosques should be built

Sayyiduna Abdullah bin Umayr al-Sadusi (may Allah be pleased with him) narrates that he brought a water vessel from the presence of the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) had washed his face, rinsed his mouth in it and put his saliva into the water, then he washed his hands and filled the vessel. He said: "Whenever you pass by any water on the way, add more water to whatever water remains in this vessel. When you reach your land, sprinkle this water on that spot and make a mosque there." The narrator says: So they made that spot a mosque. The narrator Umar says: I have prayed there.
Al-Tabarani recorded it in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat. The narrator Umar bin Shaqiq and his father were mentioned by Ibn Abi Hatim, and he did not mention any criticism or otherwise about either of them.

Sayyiduna Zayd bin Isa al-Khuza'i (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "When you build the mosque of San'a, build it to the right of the mountain called Sir."
Al-Tabarani recorded it in al-Mu'jam al-Awsat, and its chain is hasan (good).