Surah 51. Az-Zariyat, Ayah 22

I.e., both physical (rain) and spiritual (truth and guidance).

"Sustenance", here as elsewhere, includes physical sustenance, as well as spiritual sustenance. Similarly heaven or sky has both the physical and the spiritual meaning. The physical sustenance grows from rain from the sky; the spiritual sustenance comes from divine aid, grace, and mercy, and includes the Good News and the Warning which come from Revelation about the Hereafter.