10AM, the fifth hour of the day on a Sunday, belongs to Saturn. Saturn's hours were kept for endings, boundaries and binding work: the closing of matters, contracts, discipline, land and inheritance, and operations meant to restrict or slow something down. The grimoire tradition counts Saturn cold, dry and the slowest moving of the classical seven, and its hour was generally avoided for anything meant to begin or grow. Practitioners were counseled to match the work to the hour wherever the two could be arranged together, choosing an hour whose ruling planet suited the operation in hand rather than acting in whatever hour happened to be free; a working that fit its planet well was held to draw strength from the hour, while one that fought the ruling planet's nature was held to labor against it.
Because the same planet returns roughly every seventh hour through the whole day, Saturn also rules 12AM and 5PM elsewhere on this reference Sunday, so a practitioner without access to 10AM specifically could look to those instead for work of the same character. The hour sits inside a wider correspondence system built around the same seven planets: Saturn is paired with the metal lead, with black, and with Saturday, the weekday carrying its name in full as well as its first hour. A working timed to 10AM was traditionally strengthened further by choosing Saturday itself and by using that metal and color in the object the working required, and the same logic timed ordinary practical acts as well as ritual, from gathering herbs held sacred to a planet to medical treatments believed to answer best to its temperament.