Reversing entries and the Income summary?

My accounting instructor gave us notes that involved reversing entries. In his examples, he reversed wages payable account and wages expense account; but he also reversed the income summary account. In our text book, it has nothing about reversing the income summary account. Is it necessary to do this? Also, with the payables, he credited the income summary. I have an accounts receivable that needs to be reversed and I can't find any examples of that. Do I debit income summary for the receivables?