דברי הימים ב, פרק ל״ה, פסוק ז׳

King Josiah takes personal and financial responsibility to ensure the nation can celebrate the Passover on a massive scale. To make this possible, he steps forward to supply the necessary animals for the people directly from his private wealth. His giving is an act of deliberate separation and holy dedication [רש״י, מצודת ציון], serving as a special donation straight from the king himself [ביאור שטיינזלץ].

There is a distinct division of care in providing for the holiday. Josiah's contribution is intended specifically to meet the needs of the general Israelite public. At the same time, the royal officers and Levite leaders take responsibility for supplying the animals needed by the priests and the Levites [מלבי״ם]. The king makes his generous gift available to every single Israelite who is present in Jerusalem to observe the festival [רש״י, מצודת דוד, ביאור שטיינזלץ].

The sheer number of animals provided highlights the scale of the event. Josiah sets aside thirty thousand sheep and goats combined, which are allocated strictly for the Passover offerings [רש״י]. In addition to the flocks, he provides three thousand cattle. The primary approach among commentators is that these cattle are not meant for the Passover offering itself, but are instead designated for the additional festival peace offerings that accompany the holiday celebration. Ultimately, this entire abundance flows directly from Josiah's personal property [ביאור שטיינזלץ].