R’ Yishmael says: The [sacrificial] blood is lenient in the beginning and stringent in the end, and the libations are stringent in the beginning and lenient in the end: The blood in the beginning is not subject to me’ilah [but once] it left [the Court- yard] to the Kidron Valley it is subject to me’ilah; libations in the beginning are subject to me’ilah [but once] they have gone [down] to the shissin they are not subject to me’ilah.