Ezra 1:4

Whosoever remaineth. That is, Jews who chose to remain in exile. Those who were successfully established in business enterprises of one kind or another would be most likely to remain. It was only right that they should assist their returning brethren with large contributions.

The freewill offering. Permission was granted the Jews to collect financial contributions from their heathen friends for the Temple to be built in Jerusalem. It is noteworthy that the public pronouncement of Cyrus’ decree contains this appeal to the citizens of the empire without mentioning the fact that Cyrus had made provision for the rebuilding of the Temple from public funds, as is stated in the copy of the decree deposited in the government archives at Ecbatana (see on ch. 6:2). The reason is obvious. Had the proclamation mentioned the royal subsidy, few people would have felt impressed to give to the enterprise themselves. Without knowing that the government was paying part of the cost, many heathen who were friendly disposed toward the Jews may have been more willing to make private contributions.