Respect your family ties and relationships regardless if they are through blood relation or fostering/adoption relation; maintain strong bonds with one another; prohibit marriage between your foster siblings; show respect towards your fostersiblings just like you would show towards a blood sibling; follow what Prophet Muhammad did when faced with a similar situation .

This hadith speaks about the importance of family ties and relationships in Islam. It is narrated by Umm Salama, wife of Allah's Apostle, that someone suggested to him to marry the daughter of Hamza, his foster brother. However, he refused as he considered Hamza as his brother due to their foster relationship. This hadith teaches us that marriage between foster siblings is prohibited in Islam and it emphasizes on maintaining strong family ties and relationships even if they are through fostering or adoption. It also shows us how much respect Prophet Muhammad showed for his foster siblings by not marrying their daughters even though it was allowed at that time in Arabia.