Sayyiduna Salim bin Amir (may Allah be pleased with him) reports that Sayyiduna Muawiyah (may Allah be pleased with him) had a treaty with the Romans. As they were marching, they reached near their territory, and when the treaty period ended, they attacked them. A man named Amr bin Abasah came riding on a horse and said: Allahu Akbar, fulfill the treaty and do not break it. I heard the Messenger of Allah (peace and blessings be upon him) say: Whoever has a treaty with a people, he should neither strengthen nor break it before the treaty period ends or before informing them of its termination (i.e., he should not make any changes). The narrator says: Upon hearing this, Muawiyah (may Allah be pleased with him) withdrew the army.
Hadith Referenceالمنتقى ابن الجارود / كتاب الطلاق / 1069
Hadith Gradingغلام مصطفےٰ ظهير امن پوري:إسناده صحيح
Hadith Takhrijاز غلام مصطفےٰ ظهير امن پوري:«إسناده صحيح : مسند الإمام أحمد : 4/113، سنن أبي داود : 2759، سنن الترمذي : 1580، اس حدیث کو امام ترمذی رحمہ اللہ نے حسن صحیح اور امام ابن حبان رحمہ اللہ (4871) نے صحیح کہا ہے۔»