It is narrated from Hasan (may Allah have mercy on him), a man said during his illness: So much is for so-and-so and so much is for so-and-so, and my such-and-such slave is free, and he did not say that if something happens to me then it is so. Then he recovered. Hasan (may Allah have mercy on him) said: That slave will remain a slave as before.
Hadith Referenceسنن دارمي / من كتاب الوصايا / 3302
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده صحيح إلى الحسن، [مكتبه الشامله نمبر: 3313]
Hadith Takhrijاس اثر کی سند صحیح ہے۔ دیکھئے: [سنن سعيد بن منصور 375]