A narration by al-Bukhari has:

"He gave the land in Sadaqah (as an endowment) that must not be sold or gifted, but its produce must be spent (as Sadaqah)."

وَفِي رِوَايَةٍ لِلْبُخَارِيِّ : { تَصَدَّقْ بِأَصْلِهِ , لَا يُبَاعُ وَلَا يُوهَبُ , وَلَكِنْ يُنْفَقُ ثَمَرُهُ } [1]‏ .‏