Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "Something given as a gift (for temporary use) is to be returned, and people must abide by their (mutually agreed) conditions as long as they conform to what is right."
Al-Bazzar recorded it; its chain contains Muhammad bin Abd al-Rahman al-Baylamani, and he is extremely da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب البيوع / 6392
Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "Every condition that is not permitted in the Book of Allah will be counted void, even if it were a hundred conditions."
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب البيوع / 6393
Hadith Gradingمحدثین:إسناده صحیح
Hadith Takhrij«اخرجه البزار فى المسند (1295) ، أخرجه المعجم الكبير للطبراني برقم: 10869»
In one narration, it is reported from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "The wala' (right of inheritance from a freed slave) belongs to the one who frees." Then the Prophet (peace and blessings be upon him) said: "What is the matter with people that they stipulate conditions that are not permitted in the Book of Allah? Any condition that is not permitted in the Book of Allah will be counted as rejected."
Al-Bazzar recorded it with various chains, one of which has thiqat (trustworthy) narrators. It also has a "mursal" chain, whose narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب البيوع / 6394
Hadith Gradingمحدثین:إسنادہ صحیح
Hadith Takhrij«اخرجه الطبراني فى المعجم الكبير (10869 مختصرا و 11744 مطولا)»