The original text is gui zhengguo 歸正果 [cultivate oneself to yield the right fruit]. Zhengguo means enlightenment in Buddhism, while here it is used more loosely to refer to a good afterlife as described by folk religion.
In Buddhism, undergoing various trials related to the three poisons, Raga, Dvesha, and Moha, as well as enduring calamities and hardships, leads to a profound understanding of the teachings of Buddhism. This state is referred to as “attaining positive fruition.” See Baidu baike: https://baike.baidu.com/item/%E4%BF%AE%E6%88%90%E6%AD%A3%E6%9E%9C/3390645
The three poisons (Sanskrit: triviṣa; Tibetan: dug gsum) or the three unwholesome roots (Sanskrit: akuśala-mūla; Pāli: akusala-mūla), in Buddhism, refer to the three root kleshas: Moha (delusion, confusion), Raga (sensual attachment, greed), and Dvesha (aversion, hate). These three poisons are considered to be three afflictions or character flaws innate in a being, the root of Taṇhā (craving), and thus in part the cause of Dukkha (suffering, pain, unsatisfactoriness) and rebirths. See Wikipedia: https://en.wikipedia.org/wiki/Three_poisons
