Sayyiduna Abu Umamah (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "When two Muslims shake hands with each other, they are both forgiven before their palms separate."
Tabarani recorded it. Its chain contains a narrator, Muhallab bin al-Ala, whom I do not know. The rest of its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأدب / 12772
Hadith Gradingمحدثین:إسنادہ ضعیف
Hadith Takhrij«اخرجه الطبراني فى المعجم الكبير (7076) ، أخرجه المعجم الكبير للطبراني برقم: 8076»