They put him in ward, (cf. Le Numbers 24:12), because it was not declared what should be done to him. This is perplexing, because the punishment of death had been decreed in Exodus 31:14, Exodus 31:15, and Exodus 35:2. It seems an evasion to say that although death had been decreed, the mode of death had not been fixed; for
(1) it was clearly part of the Divine answer that the offence was really capital (see Exodus 35:35 a), and
1. The incident may possibly have occurred between the first institution of the sabbath (Exodus 16:23, Exodus 16:29) and the decree of death to those that broke it. There is nothing in the record as it stands here to contradict such an assumption.
2. It is more likely that it occurred after the departure from Sinai, and that the hesitation in dealing with the criminal was duo not to any real uncertainty as to the law, but to unwillingness to inflict so extreme and so (apparently) disproportioned a punishment for such an offence without a further appeal. If it be said that such unwillingness to carry out a plain command would have been sinful, it is sufficient to answer that Moses and Aaron and the elders were human beings, and must have shrunk from visiting with a cruel death the trivial breach of a purely arbitrary commandment.