瑜伽論記 13.207

13.207

義曰：要須隔三剎那，五識類等故，雖於境貪愛以五識類等故，不得隔一二念即生。又義，隔一二剎那亦有起惡。若爾，無三性並。義曰：容有此義，故於平等境時，起三性心，如前說。

The doctrinal answer is: They must be separated by three kṣaṇas because the five consciousnesses are of equal category. Although there is craving and attachment toward the object, because the five consciousnesses are of equal category, they cannot arise separated by only one or two mind-moments. Another doctrinal opinion states: There are also cases of giving rise to unwholesomeness separated by one or two kṣaṇas. If so, then the three natures do not occur together. The doctrinal answer is: This principle is admissible; therefore, when the object is neutral, the minds of the three natures arise, as stated before.