Final answer:
The commandment was an instruction for Reuven to be reunited with his mother.
Step-by-step explanation:
The commandment mentioned in the question is a quote from the book of Exodus in the Bible. The commandment was directed towards Reuven and it meant that at his age, he should be with his mother. This commandment was given in the context of Reuven being found by Pharaoh's daughter and her having compassion on him. She then asked Moses' sister to find a nurse for him, which ended up being his own mother. So, the commandment was an instruction for Reuven to be reunited with his mother.