He finally took his parents' patient, heartfelt counsel to heart.
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Two strands: 《宋史·赵普传》 on bitter-but-loyal counsel ('忠言苦口'), and 《景德传灯录》 using 老婆心 ('grandmotherly heart') for a master's nagging compassion. Combined: words that may sting, given out of grandmotherly care.