Is the testimony of a guardian accepted in favor of those under his direct custody (fi hajrihi)?

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The testimony of a guardian (such as a father or custodian) in favor of those under his direct custody (fi hajrihi) is not accepted. This is the opinion held by the majority of scholars, including Al-Sha'bi, Al-Thawri, Malik, Al-Shafi'i, Al-Awza'i, Abu Hanifa, and Ibn Abi Layla. The evidence supporting this is that the guardian is testifying concerning a matter in which he is an antagonist in the sense that he demands their rights, litigates for them, and manages their affairs, analogous to testifying concerning his own property. Furthermore, he may take from their wealth if necessary, rendering him suspect when testifying on their behalf.