Is a pledge (Kafala) valid if made using specific terms like 'guarantor for so-and-so,' 'for himself,' 'for his body,' or 'for his face'?

Primary text

The pledge is valid when one states: 'I am guarantor for so-and-so,' or uses phrases like 'for himself,' 'for his body,' or 'for his face.' This ruling extends to guaranteeing a part of the body without which life cannot be sustained, such as the head or liver, or a specific fraction of the body, such as one-third or one-quarter. The pledge is valid in these cases because the guarantor cannot produce that specific part except by producing the entire body.