大般涅槃經義記 9.97

9.97

第三嘆中，「汝言眾生有佛性故得菩提」者，正牒問辭。「如磁石」者，佛自立喻成其所說。人謂此言解上問中磁石之語，為是致惑。問中磁石，在後別解；今佛自舉磁石之喻述成問辭。「善哉」正嘆。「以性因緣故得菩提」辨理以述。

In the third part, which is the praise, "You said that because sentient beings possess the buddha-nature, they attain bodhi" directly quotes the phrasing of the question. "Like a lodestone" is an analogy established by the Buddha himself to corroborate what was said. Some people think these words explain the statement about the lodestone in the question above, which leads to confusion. The lodestone in the question is explained separately later; here, the Buddha himself cites the analogy of the lodestone to affirm and validate the phrasing of the question. "Excellent!" is the direct praise. "Attaining bodhi by virtue of the nature as cause and condition" explains the principle to affirm it.