Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) said: "Whoever builds a building should build it up to his neighbor’s (house) wall." And in another narration, the wording is: "Whoever asks his neighbor that he wants to support his building on his (neighbor’s) wall, then he should allow him to do so."