"How can they be so cruel?" the man asked, referring to his son and daughter-in-law.
"My wife and I can support him if they cannot afford to raise him. How could they sell him?"
When police interrogated the boy's father, they learned that he and his wife had agreed to sell their little boy to the couple at a meeting in a Jinjiang park on January 17. The parents - who were separated by then - took 60,000 yuan each.
"[During their last visit,] they said they were his parents and they had the right to decide what to do with him. Before that, they would take him away, but always brought him back at night," the grandfather said.
The boy's parents are facing criminal liability, while the buyers have been detained by police.
The Jinjiang story is not an isolated one. In August, a mother sold her seven-month-old baby, her second son, for 50,000 yuan ($10,700) as she felt "too tired to raise two kids", the Sanqin Daily reported.
The latest incident triggered a nationwide conversation about child trafficking and illegal adoptions. Many voices online called for harsher punishments for child trafficking.
"What should his parents do when they are released? Would it be really good for the child to return to his grandfather?" asked one weibo user.
Under Chinese law, the trafficking of women and children typically results in jail terms of five-to-10 years. In more grave circumstances, courts have issued death sentences.
China has one of the world's worst records for child trafficking, where offenders are usually involved in illegal adoption.While there is no official total, the Ministry of Public Security said 538 children went missing last year. The number hit its peak in 1990, when it stood at more than 3,400 children, according to analysis of the ministry's missing children database by news portal 163.com.
- South China Morning Post