My mother died suddenly without having made any will. I think she would have definitely given Sadaqa if she had been able to speak. Would she have a reward if I gave Sadaqa on her behalf? He (the Holy Prophet) said: Yes.
Sahih Muslim Book 12, Hadith 63
← Previous Hadith My mother who was a polytheist came to me when he (the Holy Prophet) entered into treaty with, the Quraish (of Mecca). I inquired from the Messenger of Allah (ﷺ) saying: Messenger of Allah, there has come to me my mother and she is inclined; should I (in this state of her mind) show her kindness? He said: Yes, treat her kindly.

Sahih Muslim Book 12, Hadith 62 Next Hadith → " She did not make any will," as it has been reported by Ibn Bishr, but it was not reported by the rest of the narrators.

Sahih Muslim Book 12, Hadith 64