فِي وَقْتِ الْأَزْمَةِ أَخَذَ بَعْضُهُمْ وَأَعْطَى بَعْضُهُمْ.
During the crisis, some received and others gave.
Both verbs can take objects, yet none are specified. If the intention is to contrast the activities of receiving and giving, omission shifts attention from particular objects to the actions and the people performing them.
Omission does not automatically mean “every possible object.” Whether it conveys generality, economy or irrelevance of the object must be established from the discourse.