A similar notion occurs in many Quranic passages:

Now God has lightened it for you, knowing that there is weakness in you (Q. ٨:٦٦).

Afterward, We raised them up again, that We might know which of the two parties would better calculate the time they tarried (Q. ١٨:١٢).

That He might try you [to see] which of you is fairest in works (Q. ٧٧:٢).

There are numerous traditions, recorded in Sunni sources, that maintain that chari‌
table deeds and supplication can change the divine decree (qat/.a).٢٠
As for future events foretold in the traditions related on the authority of the infal‌ lible Imams, it is relevant to point out that whenever an Imam discloses something that is bound to happen, and that is not conditional upon anything, then, such infor‌ mation falls under the category of an unalterable decree (which, as discussed previ‌ ously in this chapter, is the second type of decree-namely, the unalterable one [al‌ qatfa al-mal;ztum]).This is the type in whichbadadoes not occur because God does not give the lie to Himself or to His Prophet. However, when an Imam discloses something which is conditional on the divine will not attaching itself to something else, and when He corroborates it with an attached or unattached context, such a dis‌ closure points to a conditional decree, which is subject to bada . The information related by the infallible Imams is true even when the bada occurs in it and the di‌ vine will becomes attached to another thing. The reason is that the disclosed event is conditional upon its not being contrary to the divine will.
AI-Ayyashr has related a tradition on the authority of Amr b. al-J:Iumq (J:amq), who said:

I went to visit the Commander of the Faithful [Ali] when he was struck [with a sword] on his head. At that time he told me, "٠ •Amr, I will be leaving you all." Then he added, "In the year seventy (٦٨٩ c.E.), there will descend a calamity...." I said, "May my father and mother be sacrifice for you! Until the year seventy there will be a calamity. Would there be comfort after the year seventy" He replied, "Yes, ٠ •Amr!Indeed, after calamity there is comfort." And then he went on to mention the verse "God effaces ..."

NOTES

I. This lack of knowledge about the meaning of the word bada led scholars like Fakhr al-Razi to attribute to Shiites the false view ascribing ignorance to God. See his Tafslr on the verse "God blots out, and He establishes whatsoever He will" (١٣:٣٩).
٢. For some traditions pertaining to the will of God, see Majlisi, Bi/:lar, vol. ٤, pp. ٩٢-
١٣٤.
٣. Al-Shaykh al- aduq
Rir/a, ٢ vols. (Najaf: Al-Matbaat al-ijaydariyya, ١٩٧٠), vol. ١, p. ١٤٥, sec. ١٣, which de‌ scribes the meeting between the Imam al-Ri٤a and Sulayman al-Marwazi; and Majlisi, Bi/:lar, the section dealing with al-bada wa al naskh, in vol. ٤, pp. ٩٢-١٣٤.
٤. Majlisi, Bi/:lar, vol. ٤, pp. ٩٢-١٣٤. It has also been related by al-Kulayni from Abu
B٨$Ir; see Kashi, al-Waft, vol. ١, p. ١١٣.