Taj Mohammad tries hard to hold back his tears as he describes the most painful decision of his life.
"I had to sell my six-year-old daughter Naghma to a relative to settle an old debt," Mr Mohammad says, staring blankly at the tattered tarpaulin roof of his small mud shelter.
A shy girl with a smiling face, Naghma is now engaged to a boy 10 years older than her. Mr Mohammad says his daughter may have to leave for the boy's home in Helmand's Sangin district in a year.
His wife and mother-in-law sob inconsolably as they try to protect Naghma and her seven siblings from the harsh Afghan winter outside.
"Everyone in the family is sad," says Naghma's grandmother, who was herself a child bride. "We cry. We are in pain. But what else could we do?" she asks before answering her own question.
"The relatives wanted their money back. Taj couldn't pay, so he was forced to give them Naghma."
Silence descends on the small, one-room dingy shelter, one of hundreds at the Qambar refugee camp on the outskirts of Kabul.
The long pause is broken by the hoarse cough of a child.
"To keep my family alive, I took a loan of $2,500 [about £1,600] from a distant relative," Mr Mohammad says.
Years of war and poverty forced Mr Mohammad to leave his home in the southern province of Helmand and take refuge in Qambar's mud shelters.
He says he was struggling to come to terms with the loss of his three-year-old son and an uncle, both of whom died in the cold earlier this month, when the distant relative sent a message demanding his money back.
"He wanted his money back. But I couldn't pay. No-one would lend money to me," he says.
"Then a relative suggested that I give my daughter in lieu of money."
Naghma is too young to understand the ramifications of her father's decision.
"She only cries when we talk to her about it," Mr Mohammad says.
"If I can give my relative some money, then I can delay the marriage until Naghma is 14 or 16 years old."
The legal age for marriage in Afghanistan is 16 for women and 18 for men.
Dost Mohammad, the would-be groom's father, also lives in the Qambar camp. He agrees it is illegal to buy a child bride.
"The government doesn't allow it," he says, but adds quickly: "I consulted the tribal elders and this is their decision."
Despite the fact it is illegal under Afghan law, the practice of marrying off child brides for money is widespread in many parts of Afghanistan.
No accurate figures exist for numbers of children involved, but human rights campaigners say it is not uncommon for girls as young as Naghma to be sold.
Mohammad Musa Mahmodi, who heads the Afghanistan Independent Human Rights Commission (AIHRC), expressed his concern at what he said were "traditions and economic situations that would force families to submit to the practice of selling their children".
Cases like Naghma's go on all over Afghanistan, but are rarely reported.
Before I leave, Taj Mohammad tells me: "Our eyes are dry - even the tears are not coming to free us from our pain."